Preheat your pan over medium-high heat and add the olive oil.
Add the ground beef to the pan, breaking it apart with a spatula. Cook until browned and no longer pink, about 5-7 minutes. Season with salt and pepper and transfer to a plate, keeping the juices in the pan.
In the same pan, add the chopped onion and minced garlic, sautéing until the onion becomes translucent, around 3 minutes.
Add the broccoli florets to the pan, stirring frequently. Cook until the broccoli is tender-crisp, approximately 4-5 minutes.
While the broccoli is cooking, whisk together soy sauce or coconut aminos, sesame oil, apple cider vinegar, grated ginger, and red pepper flakes in a small bowl.
Return the ground beef to the pan with the broccoli and pour the sauce mixture over it. Stir to combine and cook for another 2-3 minutes, allowing flavors to meld.
Adjust seasoning with salt and pepper, if necessary, and garnish with sesame seeds.
Serve hot, optionally over a bed of cauliflower rice for a complete keto-friendly meal.