In a large skillet, brown ground beef over medium heat. Drain excess grease.
Add garlic, soy sauce, sriracha, and brown sugar. Stir to combine.
Toss in sliced bell peppers. Sauté for 3–4 minutes until just tender.
Pour in water or broth. Bring to a gentle boil.
Break in noodles and simmer, stirring occasionally, for 4–5 minutes until soft.
Sprinkle with green onions and sesame seeds before serving.