1/3 cup gluten-free soy sauce
1/2 cup water
3 Tbsp. rice wine vinegar
2 Tbsp. corn starch
2 Tbsp. minced ginger
1/4 tsp. freshly-ground black pepper
1 lb. thinly sliced flank steak or sirloin, cut diagonally across the grain into thin strips
2 garlic cloves, minced
2 Tbsp. olive oil
8 ounces baby portobello or button mushrooms, halved
4 ounces shiitake mushrooms, halved
3 cups chopped kale
2 green onions, thinly sliced
1. Add all marinade ingredients to a bowl and whisk to combine. Pour marinade into a large bowl or ziplock bag, then add in the steak and gently toss to combine. Cover/seal and refrigerate for at least 15 minutes.
2. Once steak has marinated, heat 1 Tbsp. oil in a large saute pan over medium-high heat. Remove steak from marinade with a slotted spoon, reserving the marinade, and add to saute pan with garlic. Saute for about 2-3 minutes until browned, stirring occasionally. Remove steak with a slotted spoon and set aside.
3. Add mushrooms, kale, and reserved marinade to saute pan, and stir to combine. Cook for 3-4 minutes, until the kale is wilted, the sauce has thickened, and the mushrooms have cooked, stirring regularly so that sauce does not burn. Add in the steak, and toss to combine.
4. Serve immediately over rice or quinoa, garnished with chopped green onions.