In a large skillet over medium heat, heat oil. Add onions, peppers, and broccoli and cook until tender, 5 minutes. Remove from the pan.
Add ground beef, season with salt and pepper, and cook until no longer pink, 5 minutes more. Drain fat and return vegetables back to the skillet
Make sauce: Whisk together soy sauce, brown sugar, apple cider vinegar, Sriracha, and garlic.
In a medium saucepan, bring water to a boil. Add ramen noodles and cook until tender, 2 minutes. Drain.
Add cooked ramen noodles to skillet and pour over sauce. Toss until completely combined. Taste and season with more salt and pepper, if necessary. Then garnish with scallions and serve.