Pat steak dry; rub with spice mix. Let stand 30 minutes. In a skillet heat 2 tsp. vegetable oil over medium-high heat. Add steak. Cook 5 minutes or until browned. Turn; cook 3 to 5 minutes more or until steak is medium rare (145 degrees F). Remove; let rest. Add onion and a pinch salt to hot skillet. Reduce heat to medium; cook and stir 7 minutes or until golden brown and softened.
Meanwhile, heat a small saucepan over medium-high. Add cumin seeds; cook and stir 1 minute or until fragrant. Add 2 tsp. vegetable oil and the garlic. Reduce heat to medium; cook 1 minute. Stir in beans and 1/2 cup of their cooking liquid; heat through. Fill tortillas with sliced steak, onion, beans, and desired toppings.