Saute 1-2 finely chopped onions on medium heat for 3-5 minutes. Add 2-3 sprigs of rosemary, a chunk of grated ginger and 3 chopped garlic cloves. Saute for 2 minutes. Add 4 tsp dark brown sugar and 1-2 tbsp of water to help it melt. When melted, add 3 tbsp worcestershire and 3 tbsp balsamic vinegar.
Cook for 2 minutes. Add 4 tbsp soy sauce, 200g tomato puree, 2 tbsp smoked paprika and tabasco/sriracha/chilli to taste. Cook until the sauce thickens. Remove rest of rosemary sprigs (leave whatever fell off in).