There’s a chill in the air when we visit Isaac At in Brighton

Some of my most memorable meals have been eaten in the cold, from freshly caught crayfish on New Zealand's South Island to a Nutella and banana-filled crepe at a Parisian Christmas market. I am not averse to braving inhospitable conditions to sample a tasty treat, as long as I know what to expect. It's a different matter when, having booked to eat at a restaurant with four walls and a roof, you discover that the temperature inside isn't much different to the outside. Which is how our evening began when we visited Isaac At, a small one-room eatery on Gloucester Street in Brighton, in the depths of winter. Although energy efficiency is perhaps par for the course at an eco-conscious establishment, which prides itself on using ethical local ingredients.

I've seen bigger en suite bathrooms than the miniscule kitchen in which three young chefs are prepping. A discreetly positioned television screen shows them at work. The dining room has an air of Scandinavian functionality. There are light wood floors and white tub chairs and a view of the street through the large shop-front windows.

Our menus detail the four-course £40 set menu which is paid for in advance - there is a seven-course tasting menu for an extra £15; a list of ingredients with their provenance and the number of food miles they've travelled; and a Sussex-heavy drinks list.

We start with celeriac, smoked apple and egg yolk. Resembling a crown from above, the thick disc of salt-baked celeriac gleams with green and gold in the form of smoked apple puree, homegrown nasturtium leaves, egg yolk gel and delicate sourdough crisps. Nothing is very warm, but baking the celeriac in a salt crust has resulted in a perfectly seasoned vegetable, its subtle flavour enhanced by the rich, smoky and crisp counterparts. A better overall balance could have been struck with a thinner round of celeriac, but it's a clever dish - and a virtuous one at that.

The fish course is a pearly-fleshed fillet of oven-baked hake partnered with razor-thin slices of slightly pickled cauliflower. The slivers of cauliflower create a hiding place for spoonfuls of satin-smooth puree. Fresh and vibrant, the parsley oil adds a much-needed splash of colour.

Next we're served a large round loaf that would happily feed a family of four. Slightly confused about the timing of its arrival, and just how prodigious it is, we notice that other diners are receiving their bread at the customary point of the meal. But as I'm yet to eat a single carb this evening, I dig in enthusiastically. Made with heritage grains from Cowfold, it's hearty and full of flavour.

Next up is Trenchmore beef (also from Cowfold), which has been thickly sliced, scattered with the separated leaves of a Brussel sprout and dotted with shallot puree. The meat juices pool appealingly in each leaf. Barbie-pink in the centre and encased in a deep mahogany crust, the beef is dense and melts in the mouth.

I can imagine a picnic of pears, cobnuts and golden butter being unpacked by children in an Enid Blyton book. A quenelle of pear sorbet sits atop slices of poached pear, a beurre noisette set cream and a cobnut cream, finished with chunks of cobnut crumb. The beurre noisette cream transports me to a faraway land of toasted hazelnuts, caramelised butter and clotted cream.

Isaac At creates uncomplicated, distilled dishes that allow the quality of the ingredients to shine through. The passion for local produce is evident, but more consideration for its diners' comfort wouldn't go amiss.

Isaac At, 2 Gloucester Street, Brighton BN1 4EW; www.isaac-at.com

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