This is popular here and with my family. The same principles apply to a Sirloin Roast but there is a lot of bone so the time to done will be a bit longer.
Smokey Low Fat Apple Pork Loin
Loins are very lean so it is important to smoke them to a critical Internal Temp (IT). The addition of a Brine adds flavor, helps maintain moisture during and after cooking and tenderizes the meat. Pork Loins are the muscle that center cut Pork Chops are cut from and though internally lean, usually come with a thin layer of Fat on the top. This can be removed easily. Pork Loins are smoked Low and Slow, 225 to 250°F and depending on the thickness, usually 3 to 6", will take no more than 2 to 4 hours to get to an IT of 140 to 150°F. It is important to understand that Pork is very safe and parasite free compared to what Grandma ate and cooked to Death, an IT of 165°F or more! The USDA says modern pork is fully cooked at an IT of 145°F. Smoking to 140° then letting the meat rest 20 to 30 minutes, tented with foil, will let Carryover Cooking let it rise to 145°F. At this temp the meat will be slightly Pink which may freak out some people but is a juicy and perfectly cooked. For those that refuse to eat pink meat, smoke to 150°F with a rest and the Pork will still be moist but no pink.
Here are a couple of Recipes you may like to try...JJ
Apple Pork Brine
2-12oz.Cans Apple Juice Concentrate
1C Apple Cider Vinegar
1/4C Molasses
1/4C Mustard
1/2C Kosher Salt
2T Pickling Spice (optional)
1T Sage, rubbed
1Gal Water
Combine all and Brine the meat at least over night, 24-48 hours would be better.
Mild Bubba Q Rub (All Purpose)
1/2C Sugar in the Raw (Turbinado)
2T Sweet Paprika (Hungarian)
1T Kosher Salt
1T Chili Powder (contains some Cumin and Oregano) Ancho Chile is same without cumin, oregano etc.
1T Granulated Garlic
1T Granulated Onion
1tsp Black Pepper, more if you like
1/2tsp Grnd Allspice
Cayenne or Chipotle Pwd to taste, start with 1/2tsp and go from there...
Apple Pork Topper
3C Apple Sauce
3T Dijon Mustard
3T Brown Sugar
2T Apple cider Vinegar
1tsp Rubbed Sage
1/2tsp Black Pepper
1/2tsp Salt
1/8tsp Cinnamon
Optional: 2-3 Apples, peeled, diced and sauteed until golden brown and tender in 2T Butter.
Place all in a pot and simmer on low until thick but still pourable. Adjust sweet/salt to taste. Spoon over Pork Roast, during last 30-60 minutes of Cook time or when an IT of 110° is reached. Serve the remainder, hot, over the pork at the table...JJ