small handful each lemon thyme,oregano and basil leaves, with a few small basil leaves kept aside
Deseed and finely slice the peppers, then finely grate the garlic and lemon zest over the peppers. Carefully slice the fennel on a mandolin, or as finely as possible with a sharp knife, then tip half the fennel into a bowl of iced water and set aside.
Heat 2 tbsp of olive oil in a large non-stick pan, cook the fish, skin side down, for 4 mins until the skin is crisp and browned, then remove from the pan.
Put 1 tbsp more oil into the pan. Fry the fennel and the marinated peppers together for 4-5 mins until soft and starting to brown. Throw in the tomatoes and the balsamic vinegar, then continue to cook for 2-3 mins until they soften and release their juices. Scatter over the olives, capers and herbs, then toss everything together.
Nestle the fish fillets, skin side up, among the vegetables, then lower the heat and simmer, uncovered, for 5-6 mins until the fish is just cooked through. Lift the fish from the pan and give the sauce a final simmer and stir, then turn off the heat. This dish is better served warm rather than hot, so don't worry about the vegetables or fish resting before you serve.
Drain the reserved fennel and pat dry with kitchen paper. Toss with the juice from half the grated lemon, 2 tbsp olive oil. To serve, spoon the vegetables into the middle of two large dinner plates. Sit the cod on top of the vegetables and top with a little fennel salad on top. Drizzle everything with a touch more oil, then scatter with the small basil leaves