Roasted vegetable pizza

To make the dough: Mix the flour, yeast, salt and sugar in a large bowl, then mix in 175ml (6fl oz) warm water and the oil to make a soft dough. Knead the dough for about 8 mins on the work surface. You shouldn't need extra flour. When the dough is smooth and elastic, put it back into the clean bowl, and cover with cling film. Leave for about an hour in a warm place for the dough to double in size. Meanwhile, set the oven to gas mark 7 or 220°C. Prepare the vegetables for the pizza topping and mix them with the oil, in a roasting tin. Roast for 15 mins, stir them, and roast for another 10 mins until just beginning to brown. Leave them to cool. When the dough has doubled in size, turn it out, knock it back and roll it out to a round about 28-30cm (11-12in) in diameter, or as big as you can to fit a heavy-based baking sheet. Put the dough on the baking sheet. Spread with ketchup, almost to the edges. Scatter the roasted vegetables on top, then sprinkle with the cheese. Bake for 25 mins. Strew rocket leaves on top to serve, with extra salad, if you like. (Not suitable for freezing).