Get a small saucepan, just large enough to fit the tuna. Place the tuna inside, top with the sliced garlic, and then gently pour all the olive oil on top. Make sure there's enough olive oil to fully cover the tuna. Note: You want the tuna fully submerged in the olive oil (try to use as small a saucepan as possible). You may also cut the tuna into smaller pieces to help it better fit int the saucepan. Cover and let marinate in the refrigerator overnight.
The next day, remove the saucepan from the refrigerator and let sit at room temperature for 15 minutes.Then turn the stove to low heat and gently poach the tuna for 5-8 minutes until the tuna is just cooked through. Turn off the heat, remove from the stove, and set aside. Now we prepare the dressing. In a small bowl, mix together two tablespoons of the olive oil (use the olive oil used to poach the ahi tuna), the dijon mustard, white wine vinegar, and the chicken broth. Scoop out the sliced garlic from the olive oil and add that to the mixture as well. Then add the sliced shallots and capers, plus a little salt and pepper. Stir to combine. Set aside. Remove the tuna from the olive oil and flake the tuna into large pieces (use a fork to do this). Then pour all the dressing over the tuna and gently fold until the dressing is evenly distributed.
It is ready to eat! I love tuna confit with a side of toasted baguette and sliced avocado. That is how we usually enjoy it. The confit is also great simply tossed with pasta (use a long noodle shape). Enjoy ^_^