Step 1 Cook the orange juice over medium heat until it is reduced by half, about 6 to 8 minutes.
Step 2 While the juice reduces, whisk together the mustard, honey, horseradish, thyme, garlic and salt and pepper to taste. Stir in the reduced orange juice.
Step 3Grill the ribs over a medium-hot fire, basting frequently with the glaze until they are medium rare and slightly charred, about 15 minutes.