Bring 6 cups of water to a boil and cook the three ramen blocks for about 2 minutes, following the package timing and discarding the seasoning packets.
Drain the noodles and shock them in cold water to stop the cooking, then toss with a little olive oil to keep them from sticking.
Chop the green and red bell peppers, cut the carrots into matchsticks, and cut the broccoli into florets.
Cut the chicken thighs into even, bite-sized pieces.
Toss the chicken with black pepper, kosher salt, cornstarch, and soy sauce until every piece is coated, then let it marinate briefly.
Heat olive oil in a wok over medium-high heat. Add the carrots first and stir-fry until they begin to soften.
Add the garlic, then the green and red bell peppers, keeping everything moving. Add the broccoli and cook until it reaches the texture you like, adding more oil if the wok looks dry.
Push the vegetables to the side, add the chicken, and cook, stirring, until it is cooked through and the thickest pieces register at least 165°F; the cook prefers thighs at 170–172°F.
Add the onion and white mushrooms and stir everything together, letting the mushrooms cook down.
Pour in the finishing sauce and mix well.
Add the ramen noodles and toss until coated and heated through, then turn off the heat.
Serve hot, with extra sauce if desired.
