Mix the yeast into the water until it is well combined. Mix 2 heaped tsp of salt into the flour, then pour in the yeast and water, and the beer. Mix the dough together, adding a little bit more water or beer if you feel it is too dry.
Once the dough ingredients have combined, knead the dough on a floured work surface, stretching and folding it for about 7-10 minutes. Once it springs back to the touch, cut it into 4 pieces.
Fold in the edges of each piece under the dough to form them into balls. Rub a little oil over each ball and leave covered with a bowl for about an hour, by which time they should have doubled in volume.
Mash up the tinned tomatoes in a bowl with a potato masher; sprinkle in the oregano, 1 heaped tsp salt and a couple of tbsp of olive oil.
When the pizza dough balls have doubled in size you can roll them out. Put them on a floured board and spoon on a couple of tbsp of the tomato sauce, spreading it out over the surface of the pizza. Tear up some mozzarella and sprinkle over the pizza, then sprinkle over some basil leaves.
Check the pizza hasn't stuck to your wooden board, then slide it onto a baking tray in the oven and cook for about 7 minutes each. Repeat with remaining pizzas.