Slow Cooker Beef and Broccoli

flank steak, cut across grain into thin slices

cup low-sodium beef broth

low-sodium soy sauce

oyster sauce

honey

rice vinegar

chili-garlic paste, Sriracha, or 1/2 teaspoon red pepper flakes, plus additional to taste

teaspoons minced garlic (about 2 large cloves)

tablespoons cornstarch

cups broccoli florets (about 2 small crowns)

Prepared brown rice or quinoa, for serving

Chopped green onions and toasted sesame seeds, optional for serving