Heat the oil in a wide pan and add the onions. Cook gently for 5 minutes uncovered then cover the pan and sweat for 25-30 minutes or until the onions are quite soft and slightly caramelised.
In a large bowl mix the flour, salt, yeast and sugar in a bowl. Beat in the milk, vinegar and egg and then, gradually, the oil. It should form a sticky dough. Cut the dough into large walnut size pieces and then press each flat with your hands on a baking tray. Spread the onions over the pizza base. Drain the sardines and mash them roughly with a fork, then spread them over the onions. Squeeze over the lemon juice and grate over some salt and lots of black pepper. Cover lightly with clingfilm and leave in a warm place for an hour to rise.
Heat the oven to Gas Mark 5, 190°C, fan 170°C. Bake for 20-35 minutes, or until the pizzas are sizzling.
Freezing and defrosting guidelines
Recipe is ideal for freezing. In order to enjoy optimum flavour and quality, frozen items are best used within 3 months of their freezing date. Always defrost and heat thoroughly before eating. For more tips on freezing and defrosting food, read our article Love Your Freezer.
You can also try our Gluten-free margherita mini pizza.
See more Christmas recipes