1. Toss the mushrooms in the oil with the garlic.
2. Toast the walnuts for 2-3 minutes under a hot broiler. Chop them coarsely.
3. Mix together the tofu and lemon juice.
4. Season well and stir into the mushroom slices.
5. Either mix in the scallions and toasted walnuts or arrange them on top as a garnish.