Into a large deep skillet over medium-high heat, add the sliced sausage. Cook until browned on both sides, approximately 5 minutes. Remove the cooked sausage from the skillet and set aside.
Into the same skillet over medium-high heat, add the olive oil. When the oil is hot, add the diced onion. Cook, stirring frequently, 2-3 minutes until onion is softened. Reduce heat to low.
Add the pesto, sea salt, and ground black pepper. Stir to combine.