Bring a large pot (filled halfway ) of water to a boil. Add Udon noodles and broccoli and cook for 3-4 min. until noodles are cooked and broccoli is crisp-tender. Drain and set aside. (If using spaghetti, cook according to package directions, adding the broccoli for the last 3-4 min. of cooking).
While the noodles are cooking, prepare the sauce. Add the orange zest, orange juice, soy sauce, red pepper flakes and ginger to a small bowl and whisk together. Set aside.
In a large non-stick skillet heat the oil over medium. Add the beef ,scallions and garlic and cook until beef begins to brown ( approx. 4 min.) Add the snow peas, red bell pepper and the orange/soy mixture and continue to sauté until beef is fully cooked (approx. 3 min.)
Add noodles/broccoli to the skillet with beef and toss to combine. Serve immediately. Garnish with additional red pepper flakes if desired.