In a mixing bowl mix together the 1/4 cup water, 1/4 cup soy sauce, garlic and black pepper. Add steak strips and marinade for 30 minutes.
Heat olive oil in large frying pan over medium-high heat. Add steak strips and marinate, fry until light pink, about 3 minutes. Don't over cook meat because it will become chewy. Take meat out of pan and set aside.
Add onion, carrots and green beans, cook for 2 minutes. Add broccoli and cook for 1 more minute. Make sure you keep stirring the ingredients the whole time so all the flavors mix well together.
In a small bowl or glass measuring cup, whisk together the cold water, soy sauce, brown sugar, ginger, sesame oil and cornstarch. Pour mixture into skillet and mix well. Cook until sauce thickens about 2-3 minutes. Add beef back to the skillet, turn off heat and mix well. Place lid on skillet and let sit 5 minutes.
Sprinkle sesame seeds on top when you serve. It's great with a side of white rice or pad thai noodles.