Stir together the crème fraîche, mayonnaise, mustard and finely chopped dill.
Season to taste with salt, pepper and freshly squeezed lemon juice.
Keep the dressing in the fridge until ready to serve.
Chilli and garlic prawns
Clean the prawns, removing the shells and the dark intestinal vein. Rinse them, then lay them on a thick layer of kitchen paper and pat dry.
Halve the courgette lengthways, scoop out the seeds with a spoon and cut the courgette into cubes.
Mix the olive oil with the garlic, chilli and parsley and season with salt and pepper.
Put the prawns and courgette in a bowl and toss well with the oil mixture. Chill and leave to marinate for about 15 minutes.
Spread the prawns and courgette in an ovenproof dish, cover with foil and bake in a preheated conventional oven (top and bottom heat) at 220°C for about 12 minutes.
Salad with chilli and garlic prawns and dill dressing
Tear the crisp lettuce into rough pieces, mix with the lamb's lettuce and divide between 4 plates or 4 bowls.
Top the salads with the diced avocado, the garlic prawns and courgette, and spoon a couple of tablespoons of the marinade from the baked prawns over each salad.
Serve the salads with the dill dressing, the lime wedges and freshly baked baguette, pitta or similar.