Slice off a little of the stem ends on each tomato and hollow out the pulp with a spoon. Reserve pulp.
Sprinkle salt inside each tomato and stand the tomato hollow side up in the baking dish. If your dish is the right size, the tomatoes should be crowded enough to stand up. If not, you can cut a very thin slice from the bottom of each one to make them flat enough to stand.
Heat olive oil in a pan over medium-high and add chopped kale, mushrooms, chili pepper, if using, and minced garlic. Season with salt and pepper and saute until kale is just starting to wilt, about 5 minutes
Remove from heat, and add cooked quinoa, reserved tomato pulp and basil to kale mixture, mixing well.
Evenly divide the filling among the tomatoes.
Cover with foil and bake for 15-20 minutes.
Remove foil, sprinkle with Parmesan cheese, and bake for 5 more minutes, until cheese is melted.
You can omit the cheese topping for a vegan option.This recipe can be made with 8 smaller tomatoes.Any grain such as rice, barley, farrow, or buckwheat can be substituted for quinoa in this recipe.