Scoop the seeds and pulp from the passion fruit with a spoon, and press it through a fine-mesh sieve. Reserve the juice (about 1 tablespoon) and discard the seeds and pulp. Put the shrimp in a small bowl, and toss with the olive oil to coat. Set a dry stainless-steel sautée pan over high heat and, when hot, add the shrimp. Sear, turning often until evenly pink, about one minute. Transfer to a nonreactive bowl, and add the reserved passion fruit juice, onion, tomato, scallion, cilantro, Tabasco sauce and salt and pepper to taste. Toss well to combine. Cover and refrigerate. Put the ahi on a plate, coat with peanut oil, and season with salt and pepper to taste. Set a dry cast-iron skillet over high heat for 2–3 minutes, and, when hot, sear the ahi for about 30 seconds on each side for rare, or about 1–1/2 minutes on each side for medium-rare. Transfer the ahi to serving plates, and spoon salsa over the tuna, letting the juices from the salsa run onto the plates.