Bring a large pot of water to a rolling boil. Add wide rice noodles and cook according to package directions until just al dente with a slight chew, typically 5-7 minutes. Drain immediately and rinse briefly with cool water to stop cooking. Toss with a small drizzle of oil to prevent sticking.

Heat vegetable or peanut oil in a large skillet or wok over medium-high heat until shimmering (about 375-400°F). Add minced garlic and stir constantly for 30-60 seconds until fragrant and just starting to turn golden. Watch carefully to prevent burning.

Add protein to the hot pan and spread in a single layer. Let cook undisturbed for 2 minutes to develop a sear, then stir-fry for 3-5 minutes for chicken (until internal temperature reaches 165°F) or 2-3 minutes for shrimp (until pink and opaque).

Toss in bell peppers, broccoli, and carrots. Stir-fry for 2-3 minutes until vegetables are tender-crisp with a slight crunch and bright color. Add a tablespoon of water if pan seems too dry.

Add cooked noodles, soy sauce, brown sugar, and red pepper flakes if using to the skillet. Using tongs or spatulas, toss everything together for 2-3 minutes until noodles are heated through, well-coated with sauce, and have a glossy sheen. Add a splash of water or broth if mixture seems dry.