Preheat oven to 400 degrees and line a baking sheet with foil or use a nonstick baking sheet. Thoroughly rinse produce and pat dry. Slice zucchini in half lengthwise. Use a spoon to gently scoop out pulp and seeds, leaving a ¼" thick shell. Chop pulp and set aside. Mince garlic. Cut tomato and mushrooms into a fine dice. Stack basil leaves, roll up tightly, and slice into ribbons (called “chiffonade”). Cut lemon in half. Zest 1 half of lemon for the sauce and garnish.

In a large bowl, combine mushrooms, zucchini pulp, 2/3 of the garlic, diced tomato (reserving a bit for garnish), nutritional yeast, dried basil, oregano, half the fresh basil, red pepper flakes to taste, and salt and pepper to taste. Once mixed, add 1 Tbsp. olive oil. Add breadcrumbs, a little at a time, until a slightly firm stuffing mixture has formed. Mixture should be a consistency that can be easily pressed together and into the zucchini.

Pack the stuffing mixture to desired amount into the hollowed zucchini, creating 6 stuffed zucchini boats. Place stuffed zucchini on prepared baking sheet and cover with foil. Bake for 25 minutes, or until the zucchini is tender. After about 20 minutes, remove foil and return to oven so the stuffing can crisp. (If you have extra stuffing, you can bake it uncovered in a baking dish for the same amount of time, or until the top is slightly browned and crisp.)

In a small bowl, whisk together remaining garlic and fresh basil (reserving some for garnish), juice of the lemon to taste, tahini, 1 Tbsp. water, a pinch of lemon zest, and salt and pepper to taste. (For a thinner sauce, feel free to add another 1 Tbsp. of water.)

On plates, arrange 3 stuffed zucchini and any extra stuffing on the side. Drizzle lemon-tahini sauce over the zucchini boats, or arrange in a dish on the side for dipping. Garnish with remaining diced tomato, fresh basil, and lemon zest, if desired.