Sprinkle pork with sugar, salt, and black pepper. Heat oil in a large nonstick skillet over medium-high heat. Add pork; sauté 2 1/2 minutes on each side or until done. Remove pork from skillet, and keep warm. Add leek, bell pepper, and garlic to skillet; sauté 2 1/2 minutes or until leek is tender. Stir in broth, juice, mustard, and red pepper; cook 2 1/2 minutes or until liquid is slightly thick, scraping skillet to loosen browned bits. Return pork to skillet, turning to coat.