In a large skillet, heat oil over medium heat. Add onion; cook and stir 4-5 minutes or until softened. Reduce heat to medium-low; cook 20-25 minutes or until golden brown, stirring occasionally. Add garlic; cook 1 minute longer.
Finely grate peel from orange. Cut orange crosswise in half; squeeze juice from orange. Stir brown sugar, vinegar, 1/8 teaspoon salt, orange peel and orange juice into onion mixture. Bring to a boil; cook 6-8 minutes or until liquid is almost evaporated.
Stir in sweet potatoes, tomatoes and apples. Return to a boil. Reduce heat; simmer, uncovered, 20-25 minutes or until apples are tender and liquid is almost evaporated, stirring occasionally.
Sprinkle pork with pepper and remaining salt. Grill, covered, over medium heat 18-22 minutes or until a thermometer reads 145°, turning occasionally. Let stand 5 minutes before slicing. Serve with ragout.