Combine ketchup, water, soy sauce, ginger, and garlic in a saucepan; bring to a simmer. Simmer 5 minutes or until slightly thickened, stirring occasionally. Combine 3 tablespoons sauce and pork chops in a bowl; toss to coat. Sprinkle with salt. Heat a large grill pan over medium-high heat. Coat pan with cooking spray. Add pork to pan; grill 4 minutes on each side or until desired degree of doneness. Remove pork from pan; let stand 5 minutes. Drizzle pork with remaining sauce; sprinkle with green onions and sesame seeds.