1
lb halibut, swordfish or tuna fillet, cut into 1-inch pieces
1
medium onion, thinly sliced
3
garlic cloves, finely chopped
1
teaspoon finely chopped gingerroot
1
box (10 oz) frozen asparagus cuts, thawed, drained
1
package (8 oz) sliced fresh mushrooms (3 cups)
1
medium tomato, cut into thin wedges
2
tablespoons reduced-sodium soy sauce
1
tablespoon lemon juice
Additional reduced-sodium soy sauce, if desired