Instructions

1. In food processor or blender, puree chipotles, adobo sauce, olive oil and lime juice. Place steak in large ziploc bag, pour chipotle mixture over. Seal bag and refrigerate at least 4 hours or up to overnight.
2. Heat cast iron skillet over medium-high heat. Remove steak from marinade; discard marinade. Pat steak dry with paper towels to remove excess marinade. Add vegetable oil to skillet. Place steak in skillet; cook 6 minutes for medium-rare, turning once halfway through cooking. Transfer steak to cutting board; let rest 10 minutes, then thinly slice steak against grain into 1/4-inch-thick strips.
3. On work surface, unfold 1 sheet of puff pastry. Use pizza cutter or sharp knife to cut it lengthwise into 3 strips (you should be able to just follow the lines where the pastry was folded). Cut each strip crosswise in half. Repeat with remaining sheet of pastry.
4. Place 2 to 3 slices of steak on each of 6 pieces of puff pastry. Divide shallots and cheese over steak. Brush all four edges of pastry with egg. Place remaining pieces of pastry over top. Use your fingers to stretch the pastry over and lightly seal the edges to form pockets, then use the tines of a fork to press and seal all sides. Transfer pockets to parchment-lined rimmed baking pan and transfer to freezer for 15 minutes.
5. Meanwhile, preheat oven to 400 degrees F. Remove pockets from freezer; place a second sheet of parchment on top of pockets, and then place a second baking pan on top of parchment (this prevents the pockets from puffing too high). Transfer to oven and bake 18 minutes. Remove top baking pan and parchment, adjust oven setting to broil and place pockets under broiler 2 to 3 minutes or until golden brown and crispy, rotating if necessary. Let stand 5 minutes before serving, or let cool completely before wrapping in foil and freezing.