For the peanut sauce, puree the garlic cloves, ginger, peanut butter, soy sauce, sesame oil, maple syrup, sriracha, rice vinegar, peanuts and water in a food processor or blender until smooth.
Pat the tofu with a paper towel. Wrap with a dry paper towel and place a heavy pan or cutting board on top to remove more liquid. Let stand for 15 minutes. Cut the tofu into 1/2-inch cubes.
Cook the udon noodles according to package instructions in boiling salted water. Drain and rinse with cold water in a colander.
Heat the oil in a large nonstick skillet over high heat. Add the tofu and cook until lightly browned, about 1-2 minutes per side. Remove the tofu and set aside on a plate.
Add the peppers, broccoli and white parts of the bok choy to the skillet. Sauté for 3-4 minutes until the vegetables are cooked but still bright and crisp.
Add the white parts of the scallions and continue cooking for 1 minute until fragrant.
Stir the udon noodles and 1/2 cup peanut sauce in the veggies.
Fold in the scallion greens, bok choy greens and sesame seeds.
Divide into serving bowls and drizzle with additional sauce as desired.