Heat 1 teaspoon of oil in a cast-iron or nonstick skillet. Arrange the tofu slice sin a single layer and cook until browned on both sides. Cool enough to handle and cut into ¼-inch cubes.
Cook the noodles in salted water per package instructions until al dente
Heat the remaining 1 teaspoon of oil in a wok.
Add the onions, ginger and garlic. Saute until the onions soften and start to brown.
Add the carrots and bell peppers. Saute, stirring over high heat, until the vegetables begin to soften.
In a small bowl, mix the peanut butter, maple syrup, rice vinegar, sesame oil, sriracha sauce and soy sauce. Add some water if it's too thick.
Pour the sauce over the veggies in the skillet and mix.
Add the noodles and the tofu and stir well to combine everything.
Sprinkle the chopped green onions over the noodles. Sprinkle on some coarsely pounded peanuts too, if you wish.