Basically this is a Caesar salad dressing, though without the raw egg. If you like, you can add a tablespoon of mayo (this is a good substitute for a raw egg is such dressings).

1-1/2 lbs potatoes, cut into slices or chunks
1 c radish, cut into slices or diced
1/2 small red onion, thinly sliced
chopped fresh parsley

1/4 c extra virgin olive oil
3 T lemon juice
1 T Dijon mustard
1 garlic clove, pressed
1 T mayo, optional
1/2 c grated Parmesan cheese
salt and pepper, to taste

1. Steam potatoes on a steamer rack until tender. Transfer to a serving bowl. Let cool some. Add radishes, onion, and parsley. Gently toss.

2. Whisk together olive oil, lemon juice, mustard, garlic clove, and mayo, if using, in a small bowl. Gradually blend in Parmesan cheese. Taste, then add some salt and pepper, remembering that Parmesan cheese is somewhat salty.

3. Add dressing to salad ingredients, tossing to coat. Serve warm or at room temperature.