If you do not have wine, add a little chicken stock.
In a small bowl, add soy sauce, water, wine, brown sugar, and corn starch whisking to combine. Set aside.
In a large nonstick skillet, heat oil on medium high heat until shimmering. Add garlic and cook for a minute or until fragrant. Add snow peas and cook until bright green and crisp tender about 3-4 minutes. Remove from pan and place on plate, set aside.
Add flank steak to skillet and cook until almost cooked through, about 6 minutes. Remove from pan and place on plate with snow peas.
Add sauce to hot pan and stir, bringing to a boil. Once thickened, add snow peas and beef stirring to combine and heated through. Garnish with sesame seeds. Serve over rice.