In a large 12-inch nonstick skillet, heat the oil over medium to medium-high heat until hot and rippling. If using meat, add it now and stir-fry until cooked through. Remove the meat to a plate.
Add the broccoli to the hot skillet (you may need to add another teaspoon or so of oil if the skillet is completely dry) and cook, stirring often, until the broccoli has turned bright green and is lightly browned, 7-9 minutes. It won't cook much more after this so it should be crisp-tender. I like a bit of bite to the broccoli but if you want it more tender, add on a few minutes cooking time.
Stir in the garlic and cook over medium to medium-high heat, stirring, for a minute or so.
Whisk together all the sauce ingredients and pour over the broccoli. Add the meat if you cooked it. Stir the ingredients together until well coated with the sauce and simmer for 1-2 minutes. Add additional salt and pepper to taste if needed.
Serve immediately over hot, cooked rice.