SAUCE: In a wide-mouth jar or small bowl, use a fork to whisk together the cornstarch with soy sauce. Once smooth, add in the remaining sauce ingredients. Whisk until smooth and set aside.
VEGGIE PREP: Prepare the veggies before you start cooking, because once you start, it all goes quickly! Halve an onion and slice very thinly. Finely mince the ginger and the garlic. Remove the stem and seeds from the red pepper and slice it very thinly. Finely chop the broccoli. Measure out the matchstick carrots. Thinly slice the green onions.
COOK BEEF: Heat a wok or large and deep sauté pan (12 inches minimum) over medium-high heat. Add 1 tablespoon vegetable oil and swirl to coat. Once the oil is shimmering, add in the onion. Cook for 4-5 minutes and then reduce the heat to medium. Stir in the ginger and garlic, stirring constantly to keep it from burning. Stir for 10-20 seconds and then push to the edges of the pan. Increase heat to high, drizzle in 1 more tablespoon oil, and add the ground beef to the center of the pan. Let it cook for 30 seconds without disturbing. Then, use a wooden spoon to break apart the meat into crumbles and cook until it's no longer pink, about 5-7 minutes (it's okay if it's not fully cooked through at this point). Integrate the onions, garlic, and ginger into the beef as you crumble and cook it.
RAMEN: While beef is cooking, place a large pot of water to boil. Open ramen packets and discard seasoning packets. Follow package directions to cook the ramen noodles (don't add any salt to the pasta water), cooking for 1 minute and 30 seconds less than the package directs. Drain noodles and immediately toss with 1 tablespoon vegetable oil. Set aside.
COOK VEGGIES: Reduce the heat to medium-high. Add the red pepper, broccoli, and matchstick carrots. It will seem like a lot, but it cooks down quickly. Stir-fry for 3-4 minutes or until mostly crisp-tender. Give the sauce one more quick stir. Add the cooked noodles and sauce to the skillet. Continue to cook, tossing everything with tongs for about 2-4 more minutes or until sauce is absorbed into the mixture and thickened nicely and the veggies are all crisp-tender. (There should still be some bite to the veggies -- they shouldn't be soggy!)
FINISHING: Taste and add additional soy sauce, Sriracha, and salt and/or pepper as needed. Top with green onions and enjoy while hot. Drizzle additional Sriracha or a small drizzle of sesame oil and sprinkle of sesame seeds on individual plates if desired.