From the terrific book The Ultimate Guide to Grilling by Rick Browne. Available on Amazon.com
1/4 cup soy sauce
1/2 cup extra virgin olive oil
4 oz. good quality tequila
2 pound choice porterhouse steak, aged
1 crushed garlic clove
2 tablespoons lime juice
2 tablespoons pineapple juice
1/4 cup melted butter
dash of balsamic vinegar
2 teaspoons lemon pepper
2 teaspoons Montreal Steak Seasoning
Mix the soy sauce, olive oil and 2 ounces of the tequila together in a small container and shake until well mixed. Put steak into Ziplock bag, pour in marinade, and marinate at room temperature for 1 hour. Drain the steak, discarding the marinade.
Mix the remaining ingredients in a small bowl. Apply to both sides of the meat, rubbing in well with your hands.
Place steak on grill over hot mesquite fire (600 degree to 700 degree), and cook until you reach the desired state, approximately 6-8 minutes per side for medium-rare. Place meat on a platter and drizzle the extra tequila over both sides of the steak just before serving.
Do not pour liquor over the meat while it is over or near an open flame unless you want to be an ignited part of the barbecue yourself!