Cut the red pepper in half and discard core and seeds. Dice half the pepper and slice the other half (put these slices to one side). Heat the oil in a pan and fry the onion, garlic and diced red pepper until tender. Chop up one of the tomatoes, then add it, and most of the herbs, to the pan. Cook for 5 minutes until softened.
Spoon this mixture into a shallow gratin dish and set the oven to Gas 4, 180ºC, fan160ºC. Cut the courgettes and remaining three tomatoes into slices the thickness of a £1 coin and layer up in the dish, along with the slices of pepper. Sprinkle with seasoning and drizzle with 2tbsp olive oil.
Bake for 25-35 mins until golden and tender. Sprinkle with the remaining herbs just before serving.