Saffron fish tea

This is an elegant soup that would not be out of place in any finedining restaurant. The original idea came from an excellent chef and old friend, Duncan Doherty, and it was part of a seven-course meal we did together for some chef friends and one of the country’s top food publications. Serves 6 2 crayfish tails (keep shells for stock) 10 prawns (keep shells for stock) 200g yellowtail 200g smoked trout 50g trout or salmon roe 10 cherry tomatoes 1 bulb fennel 10g fennel or dill tops 1.2 litres fish stock