In a medium bowl, combine diced cucumbers and thinly sliced red onion. Drizzle with apple cider vinegar and sprinkle with sugar-free sweetener, salt, and black pepper. Toss gently to marinate while preparing the beef.

Heat a large skillet over medium-high heat, add the ground beef, and cook for 5 to 7 minutes, breaking apart as it browns. Drain any excess fat.

Reduce heat to medium. Add minced garlic and sesame oil to the skillet, sautéing for 1 to 2 minutes until fragrant.

Stir in soy sauce or coconut aminos, sugar-free sweetener, rice vinegar, crushed red pepper flakes, and ground ginger. Cook for an extra 2 to 3 minutes.

Remove from heat and fold in chopped green onions and half the sesame seeds. Stir well.

To serve, plate the beef, garnish with remaining green onions and sesame seeds, and place the cucumber salad on the side.