1. Combine 3 tablespoons olive oil, pistachios, and next 5 ingredients (through mustard) in a small bowl. Add 1 teaspoon garlic and 1/8 teaspoon salt, stirring with a whisk.
2. Bring 1 1/2 cups water to a boil in a small saucepan. Add 1/4 teaspoon salt and couscous. Cover, remove from heat, and let stand 5 minutes. Fluff with a fork.
3. Heat a large skillet over medium-high heat. Rub pork with remaining 1 teaspoon garlic. Sprinkle with 1/4 teaspoon salt and pepper. Add 2 teaspoons oil to pan; swirl to coat. Add pork to pan; cook 3 minutes on each side or until done. Remove pork from pan; keep warm. Reduce heat to medium-low. Add remaining 1 teaspoon oil and tomatoes to pan; cook 5 minutes or until skins blister, shaking pan occasionally. Sprinkle with remaining 1/8 teaspoon salt. Stir tomatoes and parsley into couscous; divide couscous mixture evenly among 4 plates. Top each serving with 1 pork chop and about 2 tablespoons vinaigrette.