Trim fat from roast. Inject butter sauce evenly into pork. Combine salt, pepper, and cilantro, and rub mixture over pork. Cover pork and chill 8 hours.
Soak mesquite chips in water at least 30 minutes.
Prepare charcoal fire in smoker, and let burn 15 to 20 minutes. Drain chips, and place on coals. Place water pan in smoker; add water to depth of fill line. Place pork on lower food rack; cover with smoker lid.
Cook pork roast 4 to 5 hours or until a meat thermometer inserted into thickest portion of roast registers 160°. Prep: 30 min., Marinate: 8 hrs., Cook: 5 hrs.
*1 (7-pound) boneless pork loin roast may be substituted.
Note: For testing purposes only we used Original Cajun Marinade Injector for Cajun butter sauce.
Roasted Pork: Place pork in a roasting pan, and bake at 425° for 45 minutes; reduce oven temperature to 350°, and bake 20 more minutes or until meat thermometer registers 160°.