Heat the oven to 200C/fan 180C/gas 6. Pierce the tomatoes with a fork. Toss with some olive oil, season and bake for 15 minutes. Stone the olives.
Use 1 or 2 ovenproof dishes large enough to hold the sardines in a single layer. Put the sardines in side by side and season. Sprinkle over the lemon zest, olives and tomatoes and drizzle with more olive oil. Bake for 10 minutes. Serve with extra lemon wedges.