Ask your butcher to halve each kidney and remove the membranes and fat. Preheat the broiler. Place the oil, thyme, salt, and pepper in a dish. Add the kidneys and marinade for 30 minutes, turning a couple of times. Dry them with paper towels and put onto skewers. Preheat the oven to 450F. Broil the kidneys with the tomatoes, turning them a few times. When they start to lose their juices, take them from the broiler and finish cooking in the oven, now set to 450F for 5 minutes. Serve the kidneys very pink inside. Serve them with french fries and tomatoes and brushed with the kidney marinade flavored oil.
