Slow-Roasted Salmon With Fennel, Citrus, and Chiles

Name: Slow-Roasted Salmon With Fennel, Citrus, and Chiles
Cuisine: American
Ingredients: 1 medium fennel bulb, thinly sliced; 1 blood or navel orange, very thinly sliced, seeds removed; 1 Meyer or regular lemon, very thinly sliced, seeds removed; 1 red Fresno chile or jalapeño, with seeds, thinly sliced; 4 sprigs dill, plus more for serving; Kosher salt, coarsely ground pepper; coarsely ground pepper; 1 (2-pound) skinless salmon fillet, preferably center-cut; ¾ cup olive oil; Flaky sea salt (such as Maldon)