In the bowl of a mini food processor, add 2 chopped garlic cloves, ginger, brown sugar, soy sauce, fish sauce, white vinegar, and black pepper. Pulse until well blended. In a small sauce pan over medium-high heat bring sauce to a boil and simmer until reduced and slightly thickened, 5 minutes.
Rinse and pat steak dry with a paper towel. Season generously with salt and pepper; rub with olive oil. When cast iron pan is very hot and smoking add 1/2 teaspoon olive oil to pan. Cook steak on high heat, 3 minutes per side. Remove and transfer to plate, cover loosely with foil to rest.
Meanwhile in a large pot over medium heat add 1 tablespoon olive oil and 1 minced garlic clove. Add spinach and stir until leaves are slightly wilted. Season with salt and pepper.
Reheat sauce and stir in 1/4 cup cilantro. Slice steak across the grain into 1/2" slices and serve with garlic-ginger sauce over spinach. Garnish with remaining parsley.
This recipe is super simple, easy to make and takes all of 5 minutes for a quick weeknight meal that is full of flavor. The sauce kicks this recipe up a notch and takes it from just another flank steak to wow. Another plus is the zero carb high protein combination. This recipe was found on delish and is suitable for all waistlines.