Step 1: In a bowl, mix the soy sauce, olive oil, Dijon mustard, garlic, rosemary and black pepper. Pour over the steak set in a container and let it marinate for up to 24 hours. Remove from the refrigerator and sprinkle with ½ teaspoon salt when you are ready to cook it.
Step 2: Preheat the grill pan or grill at medium-high heat. Once it is hot, place the meat and let it cook anywhere from 4 to 5 minutes per side, depending on how well done you want the meat. You can drizzle any extra marinade right over the top of the meat while it cooks. Remove the meat from the heat and place it on a cutting board. Let it rest for 5, slightly covered. Thinly slice across the grain.
Step 3: Preheat the oven to 350°F degrees.
Step 4: Slice the baguettes, teleras or bolillos in half lengthwise and place in a baking sheet. Spread about 3 tablespoons of refried beans on the bottom half of each bread. Cover with about 3 to 4 tablespoons shredded cheese. Place in the oven and let the bread crisp and the cheese melt, for about 5 to 6 minutes. Remove from the oven.
Step 5: To make the guacamole, mix the avocado, with the scallions, cilantro, fresh jalapeño, lime juice and remaining ½ teaspoon salt, or to taste
Step 6: Top the pepitos with a generous amount of the thinly sliced meat, guacamole and sliced pickled jalapeños. Place the tops on top!
