Meanwhile, combine basil, pine nuts, garlic, lemon juice and salt in a food processor. Whirl until finely chopped.
With motor still running, gradually add oil. Add tofu and whirl until mixed.
In a frypan, sauté onion for 2-3 minutes or until softened. Add mushrooms and tomatoes and cook until they start to lose their shape. Add silver beet leaves and allow to soften.
Drain cooked pasta and stir through pesto paste and sautéd vegetables.