Add thinly sliced red onion to a jar, cover completely with white vinegar, and let sit for at least 20-30 minutes until lightly pickled.
Rinse the rice, then cook according to package instructions until tender (about 15-20 minutes). Fluff with a fork and set aside.
While the rice is cooking, grate the tofu using a box grater. Add it to a large bowl with the tandoori marinade and mix well to coat. Let marinate for at least 30 minutes.
Heat the olive oil in a large skillet over medium heat. Once hot, add the red onion and cook for 2-3 minutes until softened. Add the garlic and cook for another 30-60 seconds, until fragrant.
Add the red bell pepper and cook for 2-3 minutes, until slightly tender.
Add the marinated tofu to the skillet, stirring to combine. Sprinkle in the garam masala, garlic powder, red chili powder, turmeric, and salt. Mix well.
Cook for 3-5 minutes, stirring occasionally, until the tofu is heated through and lightly browned.
Stir in the corn and cook for another 2-3 minutes. Remove from heat and fold in the chopped cilantro.
To make the sauce, add all ingredients to a blender, adding water as needed to reach desired consistency. Blend until smooth, then taste and adjust seasoning.
Assemble bowls by layering rice, tandoori tofu, cilantro sauce, and pickled onions.