This dish is very simple and the colors of the veggies make a very pretty presentation. Absolutely love the veggie "sauce". Keep meaning to try this with chicken but haven't gotten around to it yet.
Heat 2 tablespoons oil in a 12-inch heavy skillet over moderately high heat until hot but not smoking. Saute onion and yellow pepper with salt, stirring occasionally, until golden brown, about 8 minutes. Transfer to a bowl.
Pat pork chops dry and season with salt and pepper. Heat remaining tablespoon oil in skillet over high heat until just smoking, then saute chops until browned and just cooked through, about 3 minutes on each side. Transfer chops to a platter and keep warm, covered.
Return onion and yellow pepper to skillet and add tomatoes. Saute over moderately high heat, stirring, until tomatoes are slightly wilted, about 2 minutes. Remove from heat and stir in vinegar and salt and pepper to taste.
Serve chops topped with onion, peppers and tomato.