2 (1 lb) pork tenderloins, unenhanced and trimmed
3 TBS salt
6 cups cold water
Vegetable oil spray
3 TBS sake
3 TBS mirin
⅓ cup white miso paste
¼ cup honey
1 TBS brown sugar
2 tsps Dijon mustard
1 tsp rice vinegar
¼ tsp grated fresh ginger
¼ sesame oil
PORK TENDERLOINS: Lay tenderloins on cutting board, flat side (side opposite where silverskin was) up. Hold one tenderloin at thick end with paper towels, with your dinner fork, scrape flat side lengthwise from end to end 5 times, until surface is completely covered with shallow grooves. Repeat with second tenderloin.
Dissolve salt in cold water in a large container. Submerge tenderloins in brine and let stand for 1 HOUR at room temperature.
MISO-HONEY GLAZE: In a small saucepan, bring sake and mirin to boil over MEDIUM heat. Whisk in miso, honey and sugar for 30 SECONDS to 1 MINUTE or until smooth. Remove pan from heat and whisk in mustard, vinegar, ginger and sesame oil until smooth.
Remove tenderloins from brine and pat dry with paper towels. Lay 1 tenderloin scraped side up on cutting board. Lay second tenderloin on top scraped side down so that thick end of 1 tenderloin matches up with thin end of the other.
Spray five 14-inch long kitchen twine thoroughly with vegetable oil spray. Space evenly twine underneath tenderloins and tie. Brush roast with vegetable oil and season with pepper and salt. Transfer ⅓ cup glaze to bowl for grilling reserve remaining glaze for serving.
CHARCOAL GRILL: Open bottom vent completely. Light large chimney starter filled with charcoal briquettes. When top coals are partially covered with ash, pour into steeply banked pile against side of grill. Set cooking grate in place, cover, and open lid vent completely. Heat grill for about 5 MINUTES or until hot.
GAS GRILL: Turn all burners to HIGH, cover, and heat grill for 15 MINUTES or until hot. Leave primary burner on HIGH and turn off other burner(s).
Clean and oil cooking grate. Place roast on cooler side of grill, cover and cook for 18 to 22 MINUTES or until meat registers 115°F. Flip and rotate roast halfway through cooking.
Slide roast to hotter part of grill and cook for 4 to 6 MINUTES or until lightly browned on all sides. Brush top of roast with 1 TBS glaze and grill glaze side down for 2 to 3 MINUTES or until glaze begins to char. Repeat process with remaining 3 sides of roast until meat registers 140°F.
Transfer roast to cutting board, tent with aluminum foil and let rest for 10 MINUTES. Carefully remove twine and slice roast with your kitchen carving knife into ½-inch-thick. Serve with remaining glaze.