Left over polenta crisps beautifully in a skillet and is great accompaniment to a seared skirt steak and a fresh arugula salad.
Preheat oven to 250 degrees. Heat a large cast-iron or heavy skillet over medium-high. Season steak on both sides with salt and pepper. In two batches, cook steak until browned, 6 minutes per batch, flipping once. Transfer to a rimmed baking sheet, loosely tent with foil, and keep warm in oven. Wipe skillet clean and return to heat. Add 1 tablespoon oil and cook half the polenta wedges until crisp, about 5 minutes, flipping once. Repeat with remaining oil and polenta. Transfer to sheet with steak. Add leeks to skillet, season with salt and pepper, and cook until softened, stirring frequently, 3 minutes.
Toss together arugula and parsley. Thinly slice steak against the grain and serve with salad, polenta wedges topped with leeks, and lemon wedges, if desired.