Step 1

Combine 1 tablespoon oil, chipotle, 1½ teaspoons salt, and cumin in bowl. Trim fat deposits on steak to ⅛-inch thickness. Cut steak lengthwise (with grain) into three 2- to 3-inch-wide strips. Rub chipotle mixture evenly into steak, then transfer steak to rimmed baking sheet.

Step 2

For a charcoal grill: Open bottom vent completely. Light large chimney starter mounded with charcoal briquettes (7 quarts). When top coals are partially covered with ash, pour evenly over half of grill. Set cooking grate in place, cover, and open lid vent completely. Heat grill until hot, about 5 minutes.

Step 3

For a gas grill: Turn all burners to high, cover, and heat grill until hot, about 15 minutes. Turn off 1 burner (if using grill with more than 2 burners, turn off burner farthest from primary burner) and leave other burner(s) on high.

Step 4

Clean and oil cooking grate. Arrange steak and jalapeños on hotter side of grill. Cook (covered if using gas), flipping steak and jalapeños every 2 minutes, until meat is well browned and registers 125 to 130 degrees (for medium-rare), 7 to 12 minutes, and jalapeños are blistered and charred in spots, 7 to 10 minutes. Transfer steak to clean cutting board and tent with aluminum foil. Transfer jalapeños to medium bowl and cover tightly with plastic wrap.

Step 5

Place scallions on hotter side of grill and cook until dark green parts are well charred on 1 side, 1 to 2 minutes. Flip scallions, arranging them so that dark green parts are on cooler side of grill while white and light green parts are on hotter side. Continue to cook until whites are well charred, 1 to 2 minutes longer. Transfer to bowl with jalapeños and cover tightly with plastic. Arrange 6 tortillas on hotter side of grill and cook until lightly charred, 45 to 60 seconds per side. Wrap warmed tortillas tightly in foil. Repeat with remaining 6 tortillas.

Step 6

Without peeling, stem and seed jalapeños; reserve seeds. Chop jalapeños fine and transfer to bowl. Chop scallions coarse and transfer to bowl with jalapeños. Stir in lime juice, adobo sauce, remaining 2 tablespoons oil, and remaining ½ teaspoon salt. Season with salt, extra lime juice, and reserved jalapeño seeds to taste. Slice steak thin against grain and transfer to serving platter. Serve steak in tortillas, passing salsa, lime wedges, cilantro, and crema separately.