Slice the tuna into large chunks of about 2 inches across.
Toss the tuna chunks in a large bowl with some salt to coat and set aside.
Make the sauce by putting everything but the olive oil in a food processor or blender and buzzing it to combine. With the motor running, drizzle in all but about 4 tablespoons of olive oil.
Get a large saute pan hot and add the remaining olive oil. Heat this for a minute or so, but don’t let it smoke.
Pat the tuna chunks dry with paper towels and sear them hard and fast over high heat in the pan. It could take a good 2-5 minutes to get this sear, depending on how big the chunks are and how hot the pan is.
When the fish has been nicely seared off, pour in the sauce and toss to coat the fish. Turn the heat down to medium and let this simmer for 3-5 minutes.
Serve hot or at room temperature, with tortillas, rice or crusty bread.