In a measuring cup or small bowl, whisk soy sauce, Worcestershire, red wine vinegar, chili powder, lime juice, and garlic. Put steak in a gallon size plastic bag and pour marinade over. Marinate in refrigerator for at least 30 minutes to 1 hour prior to cooking.
For the sweet potato kale hash, combine sweet potato, onion, red bell pepper, and garlic in a medium bowl.
In a measuring cup or small bowl, whisk 2 Tablespoons olive oil, chili powder, cumin, salt, and a dash of cayenne pepper and smoked paprika together. Pour over sweet potato mix and stir until the vegetables are properly coated.
Heat 1 tablespoon olive oil in a large skillet/pan on medium-high heat. Add sweet potato mix, stirring occasionally to avoid charring the vegetables. Cook for about 8-10 minutes or until the sweet potato is easily pierced with a fork.
While the sweet potato mix is cooking, heat 1 tablespoon of olive oil in a grill pan or a large skillet. Place flank steak with marinade in the pan and cook about 4-5 minutes on each side if you want medium rare. Remove from heat, placing the steak on a cutting board, and let it rest for about 5 minutes.
Once the sweet potato mix is fork tender, add kale and water to the mix, stir once, cover the pan, and let cook for 1-3 minutes. Once the kale is wilted and no longer tough, remove cover, add salt to taste. Remove from heat.
Slice steak into thin strips and serve with sweet potato hash.