Melt 1 tablespoon of the butter in a small skillet over medium heat. Add the shallot and cook until slightly softened, about 2 to 3 minutes, stirring occasionally. Transfer to a small bowl and cool 5 minutes. Add the remaining 4 tablespoons softened butter, cilantro, lime zest, salt, and chipotle pepper to the bowl with the shallots. Blend thoroughly with the back of a spoon, until uniform. Transfer mixture to a sheet of plastic wrap, shaping the butter into a small cylinder in the center. Twist the ends to make a more compact cylinder about 3½ inches long. Transfer to the refrigerator until ready to use; 45 minutes or longer.
Prepare the grill for cooking over medium-high heat (500°F).
Combine the sugar, ancho chili, chili powder, onion powder, coriander, salt, and pepper in a bowl. Pat the steaks dry. Lightly coat both sides of each steak with oil and evenly season the spice mixture. Let steaks stand at room temperature for 15 to 30 minutes.
Grill the steaks over high heat, with the lid closed, 8 to 10 minutes for medium-rare, turning once. Or cook to your desired doneness after turning at 4 minutes.
Remove steaks from the grill and let rest at room temperature for 5 minutes.
Remove the cilantro-lime butter from the refrigerator. Cut into 8 slices.
Top each steak with 1 to 2 slices of the butter, reserving any extra butter for another use.