How to Make It
Heat a grill pan over medium-high. Combine chipotle, adobo sauce, oil, 1/4 teaspoon black pepper, and 3/8 teaspoon salt. Rub mixture evenly over both sides of steak. Place steak on pan; cook 3 to 4 minutes on each side or until desired degree of doneness. Transfer steak to a cutting board; let stand 5 minutes. Cut steak across the grain into thin slices.
Heat potatoes according to package directions. Stir in sour cream, remaining 3/4 teaspoon black pepper, and remaining 1/4 teaspoon salt. Divide steak and potatoes evenly among 4 plates. Sprinkle with onions.