2½ to 3 cups extra-virgin olive oil
3 thyme sprigs
1 bay leaf
1 clove garlic, peeled and crushed
1½ teaspoons coriander seeds
1½ teaspoons black peppercorns
1 teaspoon white peppercorns
1 teaspoon fennel seeds
1 small shallot, peeled thinly sliced
1lb tuna steak
In a medium saucepan, combine the olive oil, thyme, bay leaf, garlic, coriander seeds, black and white peppercorns, fennel seeds and the sliced shallot.
Add the tuna, submerging it in the oil. Attach a candy or deep-fry thermometer to the pan and warm the oil over moderate heat to 160°F.* Cook for about 20 minute, keeping the temperature at 160ºF and then remove the saucepan from the heat and let the tuna cool at room temperature until slightly warm, about 30 minutes. Remove the tuna from the oil and place in a glass jar or bowl, just big enough to hold it. Strain the poaching oil over the tuna, using enough to cover completely.
Keep refrigerated for up to a week.
*Alternatively, put the tuna in a small baking dish, cover with the herbs, spices and olive oil and cover tightly with foil. Put in a 200ºF oven for 1 hour.