Put a large pot of salted water to boil.
Heat 2 Tbsp. oil in a large skillet. Add garlic and sauté until fragrant. Add bok choy and peppers and continue to sauté over medium-high flame, for about 5 minutes, stirring constantly. Add sauce and mix together.
Once water is boiling, cook noodles for 3 minutes, then drain and add to skillet with another Tbsp. of oil. Stir noodles and veggies; then, remove from heat. Add more peppercorn sauce if desired. Divide between two plates and top with scallions.