In a small bowl, dissolve yeast and sugar in warm water. Let stand until it starts to look a little frothy, about 10 minutes.
In a food processor, combine flour and salt. Pulse until mixed. Add yeast mixture, beer and oil. Pulse until the pizza dough comes together. Scrape dough out onto a lightly floured surface, and knead for several minutes until dough is smooth and elastic. Allow dough to rest for 2 to 3 minutes. Divide dough in half, and shape into balls. Place dough balls in separate bowls, and cover with clingfilm. Allow to rise at room temperature for about 1 hour. If you are not ready to make the pizza yet - store in the fridge overnight.
To make the sauce: Heat olive oil in a saucepan over medium heat. Stir in garlic, and cook for 1 minute. Add tinned tomatoes and tomato puree and allow to simmer for 15-20 minutes so some of the water evaporates and the sauce thickens. You can add some herbs if you like, such as oregano.
On a floured surface, shape the pizza dough into a greased 30cm (12 in) round pizza pan or roll out and place on a lightly greased baking tray. Let stand 10 minutes.
Preheat oven to 200 C / Gas mark 6. Spread pizza sauce over dough. Sprinkle over grated or thinly sliced mozzarella cheese. Top with tomato slices, if you like. Bake 15 to 20 minutes, or until crust is golden brown.