In a small bowl, using a fork, mix together the butter, chipotles, cilantro and tequila, if using. Spoon onto parchment. Using the parchment as an aid, form the butter into a 4-inch-long log; roll up tightly. Refrigerate until firm, at least 2 hours.
Preheat a grill to medium-high. Season the steaks with salt and pepper. Grill the steaks, flipping halfway through, about 5 minutes per side for medium-rare. Transfer the steaks to a platter. Cut the butter into 8 slices and serve on top of the steak.