this way, you season your dressing perfectly every time.
drain the cooked potatoes and return them to the pot. *(keep the potatoes off the heat.) add the vinaigrette to the pot of warm potatoes and using a rubber spatula, gently toss the potatoes until they are completely coated with the dressing. continue to gently toss the potatoes as they cool to become slightly warm or room temperature. *most all of the dressing will become absorbed by the potatoes. taste the potatoes and adjust the seasoning before serving.
heat the oil and 1 tablespoon butter in a large, lidded frying pan, over medium high heat. add the onion to the pan, breaking up 