Preheat the oven to 400 degrees . Season the pork chops with salt, pepper and the oregano. In a large skillet, heat the olive oil over medium-high heat until rippling. Add the chops and cook, turning once, until browned, about 4 minutes. Transfer to a baking sheet, reserving the skillet and any juices, and roast until cooked through, 12 to 15 minutes.
Meanwhile, in the same skillet, cook the red onion over medium-high heat for 3 minutes. Stir in the grapes and 1/4 cup water and remove from the heat.
Remove the chops from the oven, tent with foil and let rest for 5 minutes. Stir the spinach, almonds and balsamic vinegar into the onion mixture; season with salt and pepper. Serve the salad with the pork chops.