Combine 1/2 tbsp lime juice, oil, paprika, garlic and 1/2 tsp chipotle in a shallow dish. Add fish and turn to coat. Cover and set aside for 10 minutes to marinate.
Preheat a chargrill pan or BBQ to high. Lightly spray capsicums, zucchini and fish with oil. Cook capsicums and zucchini for 2 minutes each side or until tender. Cook fish for 2 minutes each side or until golden and cooked through.
Meanwhile, process avocado, remaining lime juice and chipotle in a food processor until smooth (or mash it, if you're like me and don't like to wash up much!).
Divide the lettuce, grilled vegetables and fish between the tortillas. Top each with a dollop of the chipotle avocado. Serve with fresh coriander and lime wedges.