Bring the stock to the boil.
Wash the clams well under running cold water.
Peel and finely dice the shallots and garlic. Thinly slice the red pepper and discard the seeds.
Pick the thyme and add the stalks to the stock.
Sweat the shallots and garlic in a splash of olive oil until soft. Add the thyme leaves and sliced red peppers and cook for a further minute. De-glaze with the sherry. Reduce by half and then add the stock.
Pick and roughly chop tarragon. Juice the lemon.
Add the clams to the broth and cook until they open. Finish with a splash of lemon juice and chopped tarragon.
Taste and season with with salt and pepper if needed.
Spoon the broth into a bowl and serve.
«Use mussels instead of clams if unavailable at your fishmonger.»