You can use any greens you like in this quick sauté, which gets terrific flavor and texture from smoky bacon, hot chile and the pop of mustard seeds. Slideshow: Recipes for Spring Produce
In a large skillet, cook the diced bacon in the olive oil over moderate heat, stirring, until golden, about 3 minutes. Add the shallot, chile and mustard seeds and cook until softened, 2 to 3 minutes. Add the greens, season with salt and pepper and cook, tossing frequently, until wilted and tender, 5 to 6 minutes. Stir in the vinegar and serve.
The cooked greens can be refrigerated overnight.