This seared tuna makes a striking, sophisticated main course. The spicy preserves are bursting with layers of flavors from the bold sun-dried tomatoes, the zesty basil, and the sharp garlic. I often prepare the preserves a day or two in advance and store them in the fridge. I also like to serve this dish as an appetizer by reducing the quantity of tuna. (I still make the same amount of preserves, however, as they always get devoured!) For less spicy preserves, remove and discard the seeds from the jalapeño. If you have more preserves than you need for this dish, they will keep in a tightly capped jar in the fridge for up to one week. Just be sure to serve them at room temperature, not straight out of the fridge.
In a food processor, combine the sun-dried tomatoes, basil, mint, jalapeño, and garlic. Pulse until the ingredients are finely chopped. Add the olive oil, the vinegar, and a quarter teaspoon each of salt and pepper. Process for a few seconds to combine, adding more oil if needed to achieve a good consistency.
Transfer the preserves to a bowl or glass jar and set aside.
Season the tuna with salt and pepper. In a large sauté pan, heat the neutral-flavored oil over high heat. Working in batches to avoid crowding, add the tuna and sear, turning once, for one minute per side. Transfer to a cutting board and let rest for three minutes.
Cut the tuna against the grain into thin slices. Arrange the tuna slices on a serving platter and drizzle with the preserves. Serve at room temperature.