Cauliflower soup with mustard croutonsPrint Recipe
2 tbsp olive oil
10g unsalted butter
5g thyme sprigs
Shaved skin of 1 lemon, plus grated zest of ½ lemon
1 large onion, peeled and thinly sliced
2 large celery sticks, cut into 3cm pieces
2 bay leaves
1 tsp caraway seeds
Salt and white pepper
1 large cauliflower, broken into small florets
1 large potato, peeled and cut into 2cm dice
1.4 litres vegetable stock (or chicken stock for non-vegetarians)
2 tbsp chopped chives
For the mustard croutons:
90g unsalted butter
3 tbsp Dijon mustard
3 tsp picked thyme leaves
3 tsp finely chopped parsley
150g crustless ciabatta, torn into 1cm pieces
These mustard croutons, adapted from those in Suzanne Goin's inspiring book Sunday Suppers At Lucques (Alfred Knopf, 2005), are a brilliant thing to have to hand and to sprinkle over gratins and salads. If you'd rather not make them, you'll need something else to perk up the soup: a teaspoon of rose harissa or some other savoury chilli sauce, swirled into each bowl before serving, would do the job perfectly well.
First make the croutons. Heat the oven to 180C/350F/gas mark 4. Put the butter in a medium saucepan on a medium heat. When it starts to foam, whisk in the mustard, herbs and a quarter-teaspoon of salt, take off the heat, leave for a couple of minutes to cool slightly, then stir in the ciabatta. Spread out on a parchment-lined baking tray and bake for 12-15 minutes, until crisp. Remove from the oven and set aside to cool. (Any you don't use for this dish, store in an airtight container.)
For the soup, put the oil and butter in a large saucepan on medium heat. Tie together the thyme, parsley and lemon skin (or put them in a tied-up muslin), and add to the pan with the onion, celery, bay leaves, caraway seeds, three-quarters of a teaspoon of salt and a quarter-teaspoon of white pepper. Cook for eight to 10 minutes, stirring often, until the onion is soft but has not taken on any colour. Add the cauliflower, potato and stock, bring to a boil, reduce to a simmer and cook for eight minutes, until the vegetables are cooked but still have some bite.
Use a slotted spoon to lift a third of the cauliflower out of the pan – avoid removing any potato – and set aside. Let everything simmer away for another five minutes, then remove the herb bundle and the bay leaves. Using a hand-held blender, or in a food processor, blitz the soup until smooth, return to the pan and add the reserved cauliflower pieces. Stir in the grated lemon zest and chives, and serve, sprinkling the croutons on top at the last minute..