Step 1

Place a chicken breast on a cutting board. Holding a knife parallel to board and working along a long side, cut through center of breast until you are ½" from the other side. Open like a book and place butterflied breast between 2 sheets of plastic wrap. Gently pound as thin as possible without tearing meat—about ¼" thick and 8" wide is ideal. Repeat with remaining breast.

Step 2

Place eggs, panko, and flour in separate shallow bowls (cake pans or pie plates work great). Season cutlets lightly with kosher salt. Working with 1 cutlet at a time, press 2 sage leaves onto both sides of meat. Wrap 2 pieces of prosciutto around each cutlet to make a belt that holds in the sage. Dredge in flour, shaking off excess. Dip in eggs, letting excess drip back into bowl. Coat in panko, pressing lightly to help it adhere, then shaking off excess. Place cutlets on a rimmed baking sheet.

Step 3

Heat vegetable oil in a large skillet over medium-high until very hot (an instant-read thermometer should register 350°–375°). Carefully lower 1 cutlet along the side of the skillet closest to you and let it slide into oil so it’s lying flat. Swirl oil in skillet carefully so that cutlet is submerged and cook just until bottom side is golden brown, about 2 minutes. Using tongs, carefully turn and cook until golden brown on the other side, about 2 minutes. Transfer to a wire rack; season with kosher salt. Let sit 5 minutes. Repeat with remaining cutlet.

Step 4

Toss scallions, peas, mint, lemon zest and juice, and olive oil in a medium bowl; season with kosher salt. Arrange cutlets on a platter and top with pea salad. Sprinkle with sea salt; serve with lemons.