Pre-heat your oven to 200C Fan/220C/425F/Gas Mark 7. Put your baking tray or pizza stone in the oven to warm up
Chop up the red pepper, red onion and leek into chunks, chop the cherry tomatoes in half. Toss the vegetables in the oil and place into a roasting tray. Season with salt and pepper if you like
Roast the vegetables in the oven for 20 minutes
When they are done, remove from the oven, and increase the oven temperature to 220C Fan/240C/475F/Gas Mark 9
Prepare your pizza doughs, then spread the tomato puree over them both, leaving a 1cm gap around the edge
Add the roasted vegetables to half of each pizza base, add the mozzarella on top, then sprinkle the herbs all over
Use your finger to dab some water on the 1cm gap around the edge of the dough. Fold the uncovered half of dough over the fillings and press the edges together. Seal by folding the dough back on itself and using your fingers to press it together tightly
Use a sharp knife or a fork to make a hole in the top of the calzone, this is to allow steam to escape in the oven
Place the calzones on some baking paper dusted with semolina or cornmeal, then use the paper to help you transfer the calzone to the hot baking tray or pizza stone that has been warming up inside the oven. Bake for 15 minutes
Serve immediately, enjoy with salad or potato wedges