Begin by thinly slicing the beef sirloin against the grain into bite-sized pieces. Shred half a head of green cabbage and slice one onion into thin rings. Mince three cloves of garlic and a one-inch piece of fresh ginger.

In a large skillet or wok, heat two tablespoons of olive oil and one tablespoon of sesame oil over medium-high heat until shimmering, about 2 minutes.

Add the sliced beef to the skillet, season with salt and pepper, and cook for about 3 to 5 minutes until browned. Remove the beef and set aside.

In the same skillet, sauté the minced garlic, sliced onion, and ginger for 1 to 2 minutes until the onion is translucent.

Add the shredded cabbage and a pinch of red pepper flakes. Cook for 5 to 7 minutes until tender yet crunchy.

Return the cooked beef to the skillet and pour in two tablespoons of soy sauce. Toss everything together for 2 to 3 minutes.

Taste and adjust seasoning as needed.

Plate the stir-fry and garnish with sliced green onions and sesame seeds.