Slice the sirloin steak and vegetables, and peel and devein the shrimp if needed.
Heat olive oil in a large skillet or wok over medium-high heat.
Add the sliced steak, season with salt and pepper, and sauté for 3 to 4 minutes until browned. Remove and set aside.
Cook the shrimp in the same skillet for 2 to 3 minutes until pink and opaque. Remove and set aside with the steak.
Add minced garlic and ginger to the skillet and sauté for about 30 seconds until fragrant.
Add bell pepper, broccoli florets, and sliced zucchini. Cook for 5 to 7 minutes until vegetables are tender-crisp.
Return steak and shrimp to the skillet. Add soy sauce (or coconut aminos) and sesame oil. Stir and heat through.
Taste and adjust seasoning with salt, pepper, or soy sauce as needed.
Remove from heat and serve, garnished with sesame seeds and sliced green onions if desired.