In a large skillet, heat the oil over medium heat until hot.
Season tuna steaks on both sides with salt and pepper; sear them in the hot skillet for 1 to 2 minutes per side or until they reach desired level of doneness.
Remove from skillet and set aside.
Add remaining ingredients to the skillet (pimiento through garlic); season with salt and pepper then cook for 4 to 5 minutes or until mixture comes to a simmer. Serve sauce over tuna steaks.