Cut the aubergines into 1cm slices, then place on a baking tray and brush with 1 tablespoon of oil.
Grill for 10 to 12 minutes, till golden brown. Turn the slices over, brush with another tablespoon of oil and grill for 5 to 8 minutes, until golden.
Peel and finely slice the onions widthways, peel and finely slice the garlic, then deseed and slice the peppers and fennel. Cut the courgettes into 1cm rounds.
In a large frying pan, heat the remaining oil over a medium heat. Add the onions and cook for 5 minutes, until they begin to soften and turn golden.
Add the garlic and cook for a few minutes, then add the peppers, fennel and courgettes, and cook for 5 to 8 minutes until they begin to soften.
Use a knife to score a cross into the base of each tomato. Put them in a bowl, cover with boiling water and leave for a minute. Remove with a slotted spoon and peel the skin.
Cut the tomatoes in half and remove the seeds with a spoon. Roughly chop the tomatoes and add to the pan, along with the aubergine and herbes de Provence.
Lower the heat, cover the pan with a tight lid and simmer gently for 20 minutes or so, until the vegetables are cooked through. Season to taste.
To make the salsa verde, remove any tough herb stalks and peel the garlic, then use a pestle and mortar to grind the herbs and garlic to a paste, adding a little sea salt to help the process (or blitz in a food processor).
Crush in the capers. Stir in the oil, finely grate in the lemon zest and squeeze in the juice, adding more oil or juice if necessary, to create a flavour and texture you like. Season to taste.
Serve the ratatouille in bowls with a spoonful of salsa verde.