Steak Tacos with Pineapple

In a small bowl, whisk the soy sauce with the garlic and ginger. Brush the mixture all over the steak and season lightly with salt and pepper. Let stand for 20 minutes. Heat a large cast-iron skillet. Add the steak and cook over high heat, turning once, until charred on the outside and medium-rare within, about 6 minutes. Transfer to a carving board and let rest for 5 minutes. Carve the steak against the grain and serve in warm corn tortillas with diced pineapple, sliced red onion and cilantro leaves.