To make the sauce: Combine chopped garlic, chopped fresh ginger, tamari or soy sauce, honey, rice vinegar, Gochujang, and 1 tablespoon toasted sesame oil in a glass jar. Shake or whisk well to combine.
Cook the brown rice noodles according to package directions until al dente. Drain thoroughly and rinse under cold water to prevent sticking.
Heat 1 tablespoon of the sesame oil (for cooking) in a large skillet over high heat. Add the mixed stir-fry vegetables and cook, stirring frequently, until they are crisp-tender and slightly wilted, about 2-3 minutes. Stir in 2 tablespoons of the prepared sauce. Cook for another minute until the sauce coats the veggies. Remove the vegetables from the pan and set aside.
In the same skillet, add the remaining 1 tablespoon of sesame oil (for cooking). Once shimmering, add the sliced beef and cook, without disturbing, for 2 minutes until deeply seared and browned on one side. Toss the meat, then pour in the remaining sauce. Bring to a simmer and cook for 1 minute, allowing the sauce to thicken slightly. Stir in the cooked noodles and the reserved vegetables. Cook for an additional 2-3 minutes, tossing constantly, until the sauce evenly coats the noodles and all ingredients are heated through.
Remove the skillet from the heat. Stir in fresh basil leaves and a sprinkle of sesame seeds. Serve immediately, topped with extra fresh basil if desired.