In a medium bowl, whisk together the soy sauce, stock, water, honey, vinegar, sugar, garlic, 1 tablespoon of oil, cornstarch, and red pepper flakes. Set aside.
Heat the remaining 1 tablespoon oil in a wok or large skillet over medium heat.
Add the steak and cook, continually stirring, until browned, 3 to 4 minutes.
Stir in the broccoli florets and sauce. Simmer until the broccoli is tender and the sauce has thickened about 4 to 5 minutes.