OK - sorry for the delayed response!
For the potato salad:
Quarter or halve about a pound of red potatoes; cover with at least an inch of cold water in a big pot and boil until fork tender. Drain and set aside.
While those cook, quarter a red onion and then cut it into very thin slices; then chop about a quarter cup of scallions - white and green parts, or whichever parts you prefer.
Finely mince garlic and whisk it with about 1 T yellow mustard and 2 T champagne vinegar, then slowly whisk in about a quarter cup olive oil. Stir in salt and pepper to taste. Then combine all the ingredients and chill, or serve at room temperature - it's also good with asparagus!