Drain artichokes, peppers and tuna separately. Clean, wash and very finely dice the zucchini. Peel and finely dice the onion. Peel garlic and chop finely. Heat oil in a pan.
Fry the zucchini, onion and garlic for 2-3 minutes. Season with salt and pepper. Dice artichokes and roasted peppers very finely. Mix crème fraîche and tapenade together. Mix with artichokes, paprika, tuna and the zucchini mixture.
Season the mixture with salt and pepper.
Pour the mixture into the cannelloni using a piping bag. Spread the rest of the filling on the bottom of an ovenproof dish. Place the cannelloni in 2 layers on top.
Preheat oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer). Wash the tomatoes. Heat butter in a pan. Sauté the tomatoes for about 1 minute. Add tomato paste and sauté briefly.
Deglaze with 200 ml water, bring to the boil once and season everything with salt, pepper and 1 pinch of sugar. Pour the tomatoes over the cannelloni. Dice the mozzarella and sprinkle over the cannelloni. Bake in a hot oven for about 35 minutes.