Whisk the sauce: In a large bowl, combine dark soy sauce, oyster sauce, hoisin, brown sugar, sesame oil, cornstarch, chicken broth, and Sriracha. Whisk until smooth. Set aside.

Cook noodles: Bring a large pot of salted water to a boil. Cook lo mein noodles (or spaghetti) according to package until al dente. Drain and set aside — toss with a tiny drizzle of oil if you don’t plan to use immediately so they don’t clump.

Sear the chicken: Heat 1 tablespoon oil in a large nonstick skillet or wok over medium-high heat. Season chicken pieces with salt and pepper. Add to hot pan and cook, stirring occasionally, until browned and cooked through, about 4–6 minutes. Remove chicken to a plate.

Stir-fry aromatics and vegetables: Add remaining oil to the same pan. Lower heat slightly if the pan smokes. Add minced garlic and ginger; stir for about 45 seconds until fragrant. Add red pepper strips, carrot shreds, spinach, and snow peas. Stir-fry for 1.5–2 minutes until vegetables are crisp-tender.

Combine noodles and chicken: Add drained noodles and the cooked chicken back to the pan.

Add sauce and toss: Pour the whisked sauce over everything. Use tongs or two spatulas to toss the noodles thoroughly, making sure every strand is coated.

Thicken on high heat: Turn heat to high and keep tossing for about 1 minute to allow the sauce to bubble and thicken. If the sauce becomes too thick, add a splash of warm water or broth and toss again.

Finish and serve: Remove from heat, sprinkle with chopped green onions, and serve immediately.