Preheat the oven to 375°F. Put the 4 tablespoons cooking fat on a large rimmed stainless-steel sheet pan.
Arrange the chicken thighs smooth-side down in one layer. Divide between two pans rather than overlapping pieces if needed.
Sprinkle 2 teaspoons sea salt evenly over the chicken.
Bake for 25 minutes. Set the hot pan on a wood trivet; the thighs should be opaque around the edges and sitting in clear-to-golden pan juices.
Flip every thigh with stainless-steel tongs. Sprinkle the remaining 2 teaspoons sea salt over the newly exposed sides.
Move the thickest thighs to the outer pan edges and the smallest thighs toward the center. Add black pepper if desired.
Bake 25 minutes more, until the thickest thigh reaches at least 165°F and the meat is opaque and juicy with light golden edges.
Rest 5 minutes. Serve whole, slice across the grain, or cube for later meals. Spoon pan juices over the chicken before serving or storing.
