- 50g/1¾oz unsalted butter
- 1 banana shallot, finely chopped
- 150g/5oz courgettes, trimmed, cut into 1cm/½in cubes
- 1 fennel bulb, cut into 1cm/½in cubes, leafy fronds reserved
- 150g/5oz carrots, peeled, cut into 1cm/½in cubes
- 100g/3½oz celery stems, trimmed, cut into 1cm/½in cubes
- 8 radishes, trimmed, cut in half from top to base
- 500g/1lb 2oz mussels, rinsed, scrubbed, beards removed (discard any mussels that do not close tightly when firmly tapped)
- 150ml/5fl oz white wine
- 750ml/1¼ pints vegetable stock
- 2 tbsp chopped fresh mint leaves, stalks reserved
- 2 tbsp chopped fresh dill fronds, stalks reserved
- 2 tbsp chopped fresh tarragon leaves, stalks reserved
- 2 tbsp chopped fresh flatleaf parsley leaves, stalks reserved
- 2 tbsp chopped fresh watercress leaves, stalks reserved
- 2 tbsp chopped fresh basil leaves
- 1 large shallot, roughly chopped
- 6 anchovies, drained, roughly chopped
- 2 tbsp capers, drained and rinsed
- ½ lemon, juice only
- 1 tsp Dijon mustard
- 4 tbsp extra virgin olive oil
- salt and freshly ground black pepper
- For the soup, melt the butter in a heavy-based, lidded saucepan over a low to medium heat. Add all of the vegetables and fry gently for 4-5 minutes, or until just softened.
- Add the mussels, wine and stock and bring the mixture to the boil. Cover the pan with the lid and reduce the heat until the mixture is simmering. Simmer for 2-3 minutes, or until the mussels have opened. (Discard any mussels that do not open during cooking.)
- For the salsa verde, put all the herbs in a food processor and pulse until roughly chopped. Add the shallot, anchovies, capers, lemon juice, mustard and oil and blend to a rough purée. Season, to taste, with salt and freshly ground black pepper.
- Remove the soup from the heat and stir in 2-3 tablespoons of the salsa verde.
- Serve immediately, with an extra dollop of salsa verde on top of each portion. (Any remaining salsa verde can be decanted into an airtight container and covered with a thin layer of olive oil. It can be kept in the fridge for up to four days.)