In a large skillet, heat over medium-high heat for about 2 minutes. Add the ground beef, breaking it apart with a spatula. Cook for 5-7 minutes until browned.

Reduce heat to medium and stir in the soy sauce, sesame oil, gochujang, minced garlic, grated ginger, erythritol, and rice vinegar. Simmer for 3-5 minutes until it thickens slightly.

While the beef is simmering, prepare the cucumber salad by slicing the cucumber into thin rounds. Combine the sliced cucumber, chopped green onions, and optional sesame seeds in a bowl. Toss gently.

To serve, layer the spicy Korean beef over the cucumber salad on individual plates. Garnish with additional sesame seeds and green onions.