Preheat your oven to 350℉ degrees and line a baking sheet with parchment paper.
Remove the stems from the portobello mushrooms and use a spoon to scrape out the gills. Save them for another use, like making soup or plant-based ground meat.
Brush each mushroom cap with ½ tablespoon soy sauce and place on the prepared baking sheet, spacing them out evenly. Bake for 10 minutes or until slightly softened but not cooked all the way through.
Meanwhile, set a nonstick skillet over medium heat and add the onion, bell pepper, and garlic. Sauté, adding a splash of water as needed to prevent the vegetables from sticking, until the onions are translucent and aromatic; 5 – 6 minutes.
Roughly crumble the tofu into the pan. Season with nutritional yeast, crushed red pepper flakes, turmeric, and kala namak (if using.) Cook for 4 – 6 minutes long, until any excess liquid has evaporated.
Fold in the spinach and cook for 1 minute, until just wilted. Turn the heat off and mix in the basil.
Divide the tofu scramble equally between the par-cooked mushrooms, mounding it up towards the centers. Bake for 10 minutes, until lightly browned on top.
Top each mushroom with sliced avocado and basil. Serve hot!