Step 1: Preheat the oven - Preheat your oven to 425°F. Starting with a hot oven helps everything cook evenly and allows the sauce to thicken nicely.
Step 2: Make the sauce - In a medium bowl whisk together the soy sauce, brown sugar, beef broth, minced garlic, ground ginger, cornstarch, and sesame oil until everything is smooth and well combined.
Step 3: Add the sauce to the pan - Pour the sauce evenly into a 9x13 baking dish or a deep sheet pan with raised edges. This liquid will become the flavorful base that cooks the noodles.
Step 4: Add the ramen noodles - Break each ramen block in half and place the noodles directly into the sauce. Let them sit for a moment so they begin absorbing the liquid.
Step 5: Season the beef - Place the thinly sliced beef in a bowl and season it with salt and black pepper. Toss lightly so the seasoning coats the slices.
Step 6: Add the vegetables - Scatter the sliced red bell pepper, yellow bell pepper, and broccoli florets evenly over the ramen noodles.
Step 7: Layer the beef - Spread the seasoned beef slices across the vegetables in an even layer. The beef will cook gently as the noodles soften beneath it.
Step 8: Cover and bake - Cover the pan tightly with foil and place it in the oven. Bake for about 20 minutes so the noodles can soften and absorb the sauce.
Step 9: Stir the noodles - Carefully remove the foil and gently stir the noodles so they finish soaking up the flavorful sauce.
Step 10: Finish baking - Return the pan to the oven uncovered and bake for another 5 minutes. The sauce will thicken slightly and the noodles will become perfectly tender.
Step 11: Add toppings - Sprinkle sliced green onions and sesame seeds over the finished dish before serving.