Green beans and strips of sirloin steak are stir-fried together in a zesty sauce flavored with lime, lemongrass, ginger, tamari, and Asian fish sauce. Prep the ingredients in advance, so when you're ready to cook, the dish will come together in under 5 minutes. Serve with rice or noodles.
Place the tamari, sugar, ginger, fish sauce, lemongrass, and lime zest in a small bowl and whisk to combine. Set aside.
Place the oil and red pepper flakes in a wok or large skillet and heat over medium-high heat until the oil is shimmering. Add the beef slices and stir fry until the meat is browned, about 1 minute. Add the reserved tamari mixture and cook, stirring constantly to coat the meat and reduce the sauce, about 2 minutes. Add the green beans and cook until they are just heated through and the coated with the sauce, 1 to 2 minutes.
Transfer the mixture to a platter and garnish with a sprinkling of chives and peanuts. Serve hot.