1.Sift flour into a bowl. Add seeds and make a well in the centre. Gradually whisk in beer and egg to make a smooth batter. Season to taste. Set aside for 30 minutes.
2.Make salsa: In a bowl, combine tomato, avocado, chilli, onion and coriander. Season to taste.
3.Make dressing: In a small jug, whisk zest, juice and cream together. Toss 1/3 of the dressing through the salsa.
4.Heat the oil in a large saucepan on high, until a small piece of bread sizzles as soon as it is added.
5.Dust fish in extra flour. Working in batches, dip fish into batter, allowing excess to drain off. Deep-fry for 3-4 minutes each, until golden and crisp. Drain on paper towel. Repeat.
6.Place 2 tortillas into each serving bowl. Fill with lettuce and salsa, then fish. Drizzle with dressing to serve.