It’s an unusually windy afternoon for spring and the sun is streaming into the windows of Vogafjós Restaurant, in Northern Iceland. A fresh loaf of rye bread, still hot from the oven, arrives at our table. A smear of butter melts almost instantly on a dark slice and the combination is utterly delicious – a texture more cake-like than the typical sandwich staple variety and with a sweeter, molassesy quality to it.

If left to my own devices, I’m convinced that I could easily subsist on loaves of this bread, accompanied with fresh pats of butter and sprinklings of sea salt. Technique is largely what makes the bread so delicious. The loaf has been baked at low heat for almost a full day at around 100 F. But the chef won’t be able to tell you at what temperature, precisely, because this bread was cooked by the heat of the earth.

The baking tradition of geyser bread, as it’s called, is just one of many Icelandic culinary techniques that take advantage of the country’s unique natural resources. As one of the youngest land masses on earth, Iceland is a hotbed of geothermal activity, which does, unfortunately, mean the occasional volcanic eruption. You might recall one that happened in 2010; plumes from the Eyjafjallajökull volcano disrupted air traffic across western and northern Europe, and over 10 million travellers were affected.

I could easily subsist on loaves of geyser bread, accompanied with fresh pats of butter.

But on this late-spring visit to Iceland, there are no ash plumes or dramatic flows of molten lava in sight. Without any destruction or disruption to worry about, Icelanders can simply use this geothermal activity as a heat source to make some tasty bread.

Earlier that morning, we visited the site where these loaves took form. I was expecting something like a cavernous enclave, but the spot where we pulled up was just another wide-open, grassy expanse. Only the clouds of steam in the distance hinted at baking.

Underground ovens reach up to 100 F where rye bread, also known as geyser bread, is slowly cooked over 24 hours

We disembark our vehicle and approach the hill, where 20-odd sheets of metal and blocks of wood, some inscribed with initials, are weighed down by bricks and lava rocks. They're covering up small holes in the ground about three cubic feet in volume. We’re warned not to step too close to the “ovens”. Our weight could cause them to collapse. The keepers of the ovens, local chefs and members of the former fishing village of Myvatn, wouldn’t be pleased.

With a heat-proof glove on one hand, our guide carefully lifts open one of the makeshift lids, but the oven inside is empty. After a few tries, he finds a plastic tub – the type you might find holding a restaurant-sized quantity of mayonnaise at Costco – but the batter inside is clearly still cooking. Each oven has a slightly different temperature and humidity, and traditionally, each family’s geyser bread has its own unique character because of this.

The heat of the earth is also being used to produce other food groups. Páll Olafsson is a fourth-generation farmer at Hveravellir Farm near Husavik, about 30 minutes away from Vogafjós. In the early 1900s, his great-grandparents used water from a nearby hot spring to melt snow that watered the tomato plants in their greenhouses. Nowadays, Olafsson is still tapping that same geyser, but he’s capturing energy for heat.

It’s a comfortable 20 C inside one of Olafsson’s greenhouses. Steam from a hot spring helps keep the environment temperate all year round. Rows of small cocktail tomatoes are flourishing, a gradient of red-and-ripe to green visibly progressing down several bunches. Honeybees buzz among the vines (there are about 160 between 11 greenhouses) which Olafsson brings in to pollinate the plants.

Olafsson's greehouse-nourished tomatoes are ready for market after just eight or nine weeks.

Compared to traditional tomato crops that could take 20 to 30 weeks to grow, Olafsson’s greenhouse-nourished varieties are ready for market after just eight or nine weeks in the warm environment. Powerful sodium lights also contribute to this quick growth, but they’re powered by the local electricity grid.

While it’s possible to convert steam energy to electricity, the technology is cost-prohibitive for a small operation like Olafsson’s, since his spring doesn’t get much hotter than 100 degrees. But he’s hopeful that technology will improve over the next five to ten years, becoming cheaper and easier to harness low-temperature steam into energy. This could take his operation fully off the grid and power it for next to nothing.

The advancement will help make Olafsson’s produce – he currently grows about 500 tonnes of tomatoes, cucumbers and bell peppers a year – more environmentally friendly and, importantly, more affordable. At the moment, tomatoes grown in Iceland are more than twice as expensive as competing produce from Spain or Tunisia, thanks to extremely low labour costs that mitigate the costs of shipping. Farmers like Olafsson are part of a cooperative that promotes the consumption of local produce and he’s noticed how competitors market their produce as “Packaged in Iceland”, accompanied by an Icelandic flag, when they’re actually just imported and shrink-wrapped in the country.

Jómfrúin, a restaurant specializing in open Danish sandwiches, is located inside gourmet food hall, Hlemmur Mathöll.

But chefs like Fanney Sigurjónsdóttir, who runs the kitchen of Skál! in Reykjavik, know the value of locally-grown produce. The menu at Skál!, which is a part of the capital’s trendy food hall Hlemmur Mathöll, isn’t strictly vegetarian. You can order beef skirt and tartare, as well as Arctic char, which swims plentifully in the waters around Iceland. But Sigurjónsdóttir’s creativity and care is best revealed in her meatless dishes.

Take the smoked carrots, for example. She cooks them with dulse, a type of seaweed, then thinly slices and stacks them on top of a slice of toasted sourdough (baked fresh by fellow food hall vendors Brauð & Co). The result is so savoury and umami-rich that I could have been tricked into thinking it was a smoked fish and not a humble root vegetable.

Sigurjónsdóttir is willing to admit that some minor lawbreaking happened to put our meal together. She blends angelica – picked from her neighbour’s yard – into her vegan mayonnaise which is spread underneath the smoked carrot toasts. We’re uncertain whether the neighbour was aware of this localized foraging effort, but Sigurjónsdóttir reassures us that the herb has long been considered a weed in Iceland.

A similar type of innocent thievery occurs in another Reykjavik kitchen. At Óx, on the popular Laugavegur Street, chef Georg Halldórsson and his intern Tómas Jóhannsson forage for angelica in Heiðmörk, a conservation area southeast of the capital.

They use stems and leaves from the herb to accent a dish of sweetbreads – the anise-like flavours pairing well with a licorice sauce that ties each bite together. It’s one of a dozen small courses served at Óx as part of an incredible dining experience with just 11 guests per seating. We’re situated in an L-shape around Halldórsson and Jóhannsson’s workstation, which is partly comprised of cupboards that came from the former home of restaurant owner Þráinn Freyr Vigfússon’s grandfather.

Óx serves up an incredible dining experience with just 11 guests per seating.

I thought the intimacy of an open kitchen might make the chefs feel shy or timid about their craft, or bothered by questions about techniques and where the ingredients are sourced (answer: everywhere from local ceramic artists to Ikea). But it was the opposite for this pair, who became animated with their guests’ excitement and curiosity. Seldom do chefs get the chance to see customers happily devouring the food that they’ve so meticulously honed and tweaked, or introduce dishes first-hand so that guests can understand why a certain herb or spice was used – or, what forest it was picked in.

Open only for a few short weeks at the time we visited, tourists were still an anomaly at Óx, so the chefs were eager to hear where we’d been, and what we had eaten. Upon hearing of our newly-formed geyser bread obsession, Halldórsson was keen to share a loaf with us. It was already planned as the sixth dish of our meal and I was well aware of how and why this bread is worthy of being its own course among 12.

Halldórsson happily posed for a few snaps with the loaf, still in a reused milk carton, before he opened the encasement and sliced up the bread inside. This one was cooked in Geysir, about 1.5 hours from Reykjavik (the irony of eating geyser bread from Geysir is not lost on me), and was reheated in the restaurant for our consumption. Butter, hand-churned from cream the day before, accompanied the bread.

Now, multi-course meals such as the one we were halfway through typically demand strategic eating habits – forgo the breadbasket, for one. I could tell that the rest of the meal was going to pack a wallop, but I happily polished off the slices served to me and wished there were more.