How to Make It
In a large, deep skillet, heat the olive oil. Add the bacon and cook over moderately high heat, turning once, until crisp, about 6 minutes. Drain the bacon on paper towels, leaving the fat in the skillet. Coarsely chop the bacon.
Add the onion and garlic to the skillet and cook over moderate heat, stirring occasionally, until softened and lightly browned, about 6 minutes. Add the kale, season with salt and pepper and toss to wilt slightly. Stir in the tomatoes and vinegar, cover and cook over high heat until the kale is tender and the tomatoes are slightly broken down, about 5 minutes. Stir in the bacon and serve right away.