Step 1: Preheat your oven to 400°F (200°C). Prepare your vegetables by cleaning and slicing the mushrooms, leaving cherry/grape tomatoes whole, and cutting the red onion into thick wedges.
Step 2: In a large mixing bowl, combine the prepared mushrooms, tomatoes, and red onion. Drizzle with olive oil, add minced garlic, dried oregano, sea salt, and black pepper. Toss thoroughly until all vegetables are evenly coated.
Step 3: Spread the seasoned vegetables in a single layer on a large baking sheet. Ensure not to overcrowd the pan; use two if necessary, as overcrowding will steam the vegetables instead of roasting them, hindering proper browning and flavor development.
Step 4: Roast in the preheated oven for 20-25 minutes, or until the vegetables begin to soften and develop some browning at the edges. Halfway through, give them a gentle stir to promote even cooking and color.
Step 5: Remove the baking sheet from the oven. Drizzle the roasted vegetables with soy sauce and sprinkle with nutritional yeast (if using). Toss gently to coat. Return to the oven and continue roasting for another 10-15 minutes, or until the vegetables are tender, deeply caramelized, and fragrant.
Step 6: Once roasted to perfection, transfer the vegetables to a serving platter. Drizzle generously with balsamic glaze. Garnish with fresh chopped parsley or basil, if desired, for a burst of freshness and color.
Step 7: Serve these Umami Bomb Roasted Vegetables immediately as a fantastic side dish, over your favorite grains or pasta, or alongside grilled protein. Enjoy the profound savory flavors!