4 slices bacon, cut crosswise into 1/2-inch pieces
2 teaspoons olive oil
1 large shallot, finely minced
Salt & Pepper to taste
Fill a stockpot with salted water, as if you were making pasta. Sort through the greens, trimming and removing any coarse stems. When the water has come to a rolling boil, drop in the dandelion greens. Blanch in the boiling water briefly, about 2 minutes, and drain. Chop roughly. Mix the vinegar and mustard in a small bowl and set aside.
Place the bacon in a medium skillet. Over low heat, cook the bacon slowly until it's barely done and the fat is rendered. Remove the bacon with a slotted spoon and set aside. Pour off the fat and discard. In the same pan — there's no need to wash it — add the olive oil. Add the minced shallot and cook over the lowest heat until softened. Add the greens back to the pan, followed by the vinegar-mustard mixture. Toss the mixture together until just warmed through, add the bacon back in, and season to taste with salt if necessary and generous grindings of black pepper. Serve immediately.