Marinate the dorado. Place the fish in a bowl, sprinkle with salt on all sides, pepper, sprinkle with thyme. Rub well. Place the lemon cut into rings in the belly of the fish. Sprinkle the carcass with lemon juice. Grease with vegetable oil. Put in the refrigerator for 20 minutes.
Grill the fish on an electric grill. Heat the grill to 230 degrees, put the dorado in. Lower the top lid, but do not press the fish. You need to fix it so that it does not touch the carcass. Otherwise, a lot of juice will be released. Grill the fish for 4 minutes, turn over and grill the other side for another 4 minutes.