Wash the broccoli and cut into even, bite-sized florets.

In a small bowl, whisk together the broth, soy sauce, oyster sauce, brown sugar, and sesame oil. Set aside.

In a separate small bowl, mix the cornstarch and cold water to create a smooth slurry. Set aside.

Bring a large pot of salted water to a boil. Blanch the broccoli florets for 60 to 90 seconds until bright green but still crisp. Drain immediately and rinse under cold water. Shake dry.

Heat the vegetable oil in a large skillet or wok over medium-high heat. Add the minced garlic, ginger, and red pepper flakes. Sauté for 30 to 45 seconds until fragrant, being careful not to burn the garlic.

Pour the prepared sauce mixture into the skillet and bring to a gentle simmer.

Stir the cornstarch slurry once more, then pour it into the simmering sauce. Stir continuously for 30 to 60 seconds until the sauce becomes glossy and thickens.

Add the blanched, drained broccoli to the skillet. Toss well to coat all the florets evenly in the sauce. Cook for 1 minute just to heat through.

Remove from heat, garnish with sesame seeds or fried garlic, and serve immediately.