3 1/2 pounds pork tenderloins
6 cups orange juice, divided
2 teaspoons salt
2 tablespoons butter
3 large shallots, finely chopped
1 cup dry white wine
2 3/4 cups low-salt chicken broth
2 Tablespoons chopped fresh cilantro
1 Tablespoon chopped fresh chives
1 Tablespoon minced canned chipotle chiles in adobe
Divide pork between 2 resealable plastic bags. Add 1 cup orange juice and 1 teaspoon salt to each bag; seal. Turn to coat. Chill at least 3 hours or overnight, turning bags occasionally.
Melt butter in heavy large saucepan over medium high heat. Add shallots and saute until soft but not brown, about 2 minutes. Add wine and boil until reduced to glaze, about 10 minutes. Add remaining 4 cups orange juice and broth; boil until reduced to 1 3/4 cups, about 45 minutes. (Sauce can be made 1 day ahead. Cool, then cover and chill.)
Prepare barbecue (medium-hight heat). Drain pork; pat dry. Discard marinade. Grill pork until thermometer inserted into thickest part of meat registers 150 degrees F for medium, turning often, about 18 minutes. Transfer to work surface; tent with aluminum foil to keep warm. Let stand 10 minutes.
Meanwhile bring sauce to simmer; mix in cilantro, chives, and chipotle chiles. Season sauce to taste with salt and pepper. Slice pork. Serve with sauce