Begin preparing noodles of choice according to package directions. Cook or soak until they are slightly undercooked/very al dente. (They will finish cooking in the sauce.) Some brands of rice noodles will only require presoaking in hot water.
When noodles are almost done precooking/presoaking, mix together ingredients for sauce in a small bowl or measuring cup.
3 tablespoons soy sauce, 2 tablespoons rice vinegar, 1 tablespoon brown sugar, 1/2 tablespoon toasted sesame oil, 1 tablespoon chili paste, 1 teaspoon cornstarch
In the skillet or wok you used to pan fry your tofu, heat a teaspoon of vegetable oil over medium-high heat. Stir fry onions for 1-2 minutes, until they start to become slightly translucent.
Add in broccoli and a small splash of water and cover the pan to trap the steam. Steam the broccoli for about 3 minutes, or until it is *almost* cooked to your preferred level of doneness. Add an extra splash of water if the pan dries out. (If you are adding in any additional veggies that have a longer cook time, e.g. cabbage, kale, green beans, mushrooms, you can add them during this step too.)
Remove the lid and add in your sliced red peppers and julienned carrots. (This is also where you would add in any other veggies that have a shorter cook time, or things you want to keep slightly crisp.) Stir-fry for 2-3 minutes, until they are almost cooked to your preferred level of doneness.
Give the sauce a stir (the cornstarch tends to settle to the bottom), then add it to the pan. Reduce the heat a little if the pan is too hot and the sauce starts to spatter.
Add in the noodles along with the pan-fried tofu. Toss to coat everything evenly with the sauce (tongs are useful here). Allow to cook, stirring occasionally, for an additional 1-2 minutes, until the noodles are cooked through and the sauce has thickened. If the noodles seem a little dry or the sauce is not coating the noodles, you can add an additional tablespoon of water at a time and stir to combine, until you have the right consistency.
Taste and adjust your noodles to preference. Depending on the variety and exact quantity of noodles you used, you made need to add an extra splash of soy sauce (or you can simply use salt) so they're perfectly seasoned.
Serve with any toppings you like. My favorites are fresh sliced scallions, toasted sesame seeds, and a little extra sriracha or chili crisp. Enjoy!