How to Make It
Heat oil in a 10-inch cast-iron skillet over a medium-high, tilting pan to coat the bottom. Arrange potato wedges and sausage slices in skillet in a single layer, and sprinkle with 1/4 teaspoon salt. Cook until potatoes and sausage are beginning to brown, 3 to 4 minutes. Using a wide metal spatula, flip potatoes and sausage, and cook until potatoes are browned and tender when pierced with a fork and sausage is crisp, 3 to 4 minutes.
Push potatoes and sausage to one side of the skillet. Reduce heat to medium-low. Add onion and cook, stirring occasionally, until translucent and slightly browned, 5 to 6 minutes. Using the spatula, flip potatoes and sausage on top of onions (to keep them from burning).
Add kale to empty side of pan, and sprinkle with remaining 1/4 teaspoon salt. Cook, stirring occasionally, until wilted, 3 to 4 minutes. Taste and add additional salt, if desired.
Arrange onions, sausage, and kale on a serving plate, and place potatoes on top of onions. Sprinkle with chopped parsley, and serve with lemon half.