Heat oil in a large (not nonstick) frying pan over medium-high heat. Season pork chops on both sides with 1/4 tsp. each salt and pepper and brown on both sides, 5 minutes total. Transfer chops to a plate.
Add onion and chiles to pan, reduce heat to medium, and cook, covered, until onion softens, about 10 minutes. Stir in tomatoes, garlic, and oregano and cook 5 minutes more, covered.
Nestle pork chops into tomatoes and onion and add 1 1/2 cups purslane. Cover and cook 7 minutes, stir in remaining purslane, and cook just until slightly wilted, about 3 minutes more. Stir in lemon zest, juice, remaining 1/4 tsp. salt, and pepper to taste.