Put the vinegar, mustard, honey, and salt into a small jar. Screw on the lid and shake vigorously. Add the oil to the jar, return the lid and shake again until the ingredients form a smooth emulsion. Dip a lettuce leaf to be sure the taste is to your liking. Adjust any ingredients if needed. If not, drizzle a moderate amount of dressing over the salad. Toss well. Taste. Add a little more dressing if needed and toss again.