How to Make It
Combine cilantro, lime juice, mayonnaise, serrano, poblano, orange juice, kosher salt, and 1/3 cup oil in a food processor. Process until mostly smooth with flecks of cilantro still visible, about 20 seconds. Transfer to a medium bowl; cover and chill until cold, at least 30 minutes or up to 3 days.
Heat 2 teaspoons olive oil in a medium skillet over high. When oil is shimmering, add tuna to skillet. Cook until browned but rare in the center, about 1 minute per side. Immediately remove from skillet, and transfer to a cutting board. Cut tuna into 24 (1/8-inch-thick) slices.
Spoon 2 tablespoons of cilantro-chile sauce onto each of 4 serving plates. Reserve remaining sauce for another use. Top each serving with 6 tuna slices, 1 1/2 teaspoons jicama, 1 1/2 teaspoons passion fruit pulp, and 1 1/2 teaspoons mango. Drizzle each plate with 1/2 teaspoon oil, and sprinkle with flaky sea salt to taste. Serve immediately.