Lentil, lemon and ginger soup

Starter: Serves 4-6. Total time: 90 minutes

One of the liveliest lentil soups (for which you cannot have too many recipes) I have tasted of late has been at the hands of veteran café pioneers Caroline Brett and Sam Russell at Heartstone in Camden, north London. This is thick and nurturing in a January kind of way, its zest being a generous squeeze of lemon at the very end, a splash of olive oil and a spoon of sweet, caramelised onions.

Soup

4 tbsp extra virgin olive oil
4 carrots, peeled and sliced
1 celery heart, trimmed and sliced
2 red onions, peeled and chopped
5cm knob of fresh ginger root, peeled and finely chopped
6 garlic cloves, peeled and finely chopped
225g red lentils
225g yellow split peas
2l vegetable stock
sea salt, black pepper

Garnish

2 tbsp extra virgin olive oil, plus extra for drizzling
2 white onions, peeled, halved and sliced as finely as possible
4 squeezes lemon juice

Heat the olive oil for the soup in a large saucepan over a medium-low heat, add the carrot, celery, red onion, ginger and garlic, and sweat, stirring occasionally, for about 20 minutes until soft and aromatic. Rinse the lentils and split peas in a sieve under the cold tap, add them to the pan and cook for 4-5 minutes, stirring occasionally. Pour in the vegetable stock, bring to the boil and simmer over a low heat for one hour, by which time the split peas should be nice and mushy.

While the soup is cooking, melt the two tablespoons of olive oil in a large frying pan over a very low heat. Add the white onions and cook for 40-50 minutes, stirring frequently, especially towards the end when they may catch and burn. They should finish upa deep, even gold. Transfer these to a bowl.

Liquidise the soup in batches with some salt and pepper – it should be very thick, the consistency of a thin purée. Ladle it into warmed soup bowls, squeeze a little lemon juice over each serving, then drizzle over some olive oil and finally strew with the caramelised onions.