Vinaigrette is a simple blend of oil, vinegar, salt, and pepper. Mustard is also commonly added. You can also add an extra flavoring or two, such as herbs, scallions, garlic, cheese, horseradish, poppy or sesame seeds, or a bit of sugar or honey. If you're using fresh herbs, add them just before using the dressing.
Serve lobster precracked so that it is easy for guests to pick up and eat. The tails are sliced and rearranged into their shells for an attractive presentation, and drawn butter is served warm for dunking.
The peanut dressing can be made ahead and refrigerated in an airtight container up to four days; bring it to room temperature before using. You can let this slaw stand for up to one hour after dressing it; if you do so, stir in the peanuts and red radishes just before serving so they stay crunchy.