Sift the flour, salt and bicarbonate of soda in a mixing bowl. Stir, then make a well in the centre.
Add the milk and lemon juice. Mix together to form a dough.
Turn the dough out onto a floured surface and knead briefly into a ball then, using a rolling pin, roll your dough into a thin rectangle approximately 30cm x 25cm (12 inches by 10 inches inches) wide.
Transfer onto a lined baking sheet and bake for 5 minutes. Remove the base from the oven.
Turn the oven up to 230C (210C fan, 445 F)
Top the pizza
If the base has puffed up, gently flatten it down with the back of a spoon.
Season the passata with salt and pepper. Spread on top of the pizza, using the back of a spoon to spread evenly across the base.
Tear the mozzarella and arrange on top of the pizza. Season with salt and pepper.
Bake in the oven for a further 5 minutes until the base is crisp and the cheese is melted and just starting to caramelise at the edges.
Transfer to a board, scatter with basil leaves and serve.