If the onions are already peeled skip to the next step. Otherwise: trim the stem end flush with the onion top, and snip off any roots hanging out of the root end. Bring a pot of water to boil and carefully add the onions. Blanch for 1 minute, and remove to a bowl of very cold water. When cool to the touch, peel each of the onions.

Heat the olive oil/butter in a medium saute pan over medium heat until shimmering. Add the onions, plus a pinch of salt, and saute until the onions are lightly golden (about 5 minutes).

Add the vinegar, water/stock, and sugar/honey and stir to mix. Increase the heat and bring to a light boil, then reduce heat to maintain a gentle simmer. Add the thyme and bay leaf and a pinch of salt and pepper. Cook for 10 to 15 minutes, turning the onions at regular intervals and spooning the vinegar mixture over them. When the vinegar mixture thickens slightly (i.e., when it thinly coats the back of the spoon), remove the pan from the heat. Serve hot.