Slice the top of the tomatoes off (keeping each top close to its corresponding tomato), then scoop the flesh out of them using a teaspoon. Leave enough around the edge so that the tomato ‘shell’ stays intact. Put the flesh straight into a food processor* and add the 6 tablespoons olive oil, 2 tablespoons tomato puree, garlic, sugar, salt and pepper. Whizz to combine and make a sauce.
Now slice the tops off the peppers (keeping the tops close by) and scoop out the pith and seeds. Finish by rinsing the insides under the tap, then arrange the empty peppers and tomatoes in a large baking dish (keeping the tops close by).
Now pre-heat the oven to 200C / 390F. Heat up a big drizzle of olive oil in a large saucepan and add the onions, red bell pepper (or zucchini), and carrot. Cook and stir for a few minutes until softened, then add the beef. Cook again, stirring, for another few minutes until the meat has browned.
Add the rice, canned tomatoes, 2 tablespoons tomato puree and about 180 ml / ¾ of a cup of water**, combine well, then cover and leave to simmer on a low-ish heat for about 10 minutes, until the rice is partly cooked. Stir through the parsley and mint, and plenty of salt and pepper.
Use the rice and meat filling to stuff the tomatoes and peppers until about ¾ full***, then cover with the veggie tops. Poke the potato wedges in between the veggies.
Pour the tomato sauce that you made in the food processor all over the tomatoes and peppers and potatoes, along with 250 ml (1 cup) water. Cover the baking dish with aluminium foil and bake for 1¼ hours, removing the foil half way through cooking.
Serve a tomato and a pepper for each person, spooning some of the tomato sauce over. Serve with a wedge of feta and crusty bread.