2 pounds red potatoes, scrubbed well and cut into 3/4-inch pieces
2 handfuls of spinach
Coarse salt and freshly ground pepper
2 tablespoons white wine or red wine vinegar
1 1/2 teaspoons Dijon mustard (I used whole grain dijon)
2 tablespoons extra virgin olive oil
3 ounces crumbled feta cheese (1/2 cup)
1 celery stalk, finely chopped
1 small shallot, finely chopped
2 tablespoons finely chopped fresh flat leaf parsley
lots of pepper, to taste
red pepper flakes, if desired
handful of bacon pieces, optional
1/2 cup bean sprouts, optional
1/2 chopped red onion, optional
Cover potatoes with water in a medium saucepan; season with salt, and bring to a boil. Reduce heat, and simmer until tender, 10 to 12 minutes. Drain, reserving 1 tablespoon cooking liquid. Let potatoes cool for 5 minutes. Cook spinach and bean sprouts (if usin) in small pan or skillet with a bit of oil until wilted.
Whisk together vinegar, mustard, and reserved cooking liquid. Add oil in a slow, steady stream, whisking constantly until emulsified.
Transfer potatoes, spinach, and sprouts to a bowl, and drizzle with vinaigrette. Gently stir in feta cheese, celery, shallot, and parsley. Season with salt and lots of pepper, plus red pepper flakes, if desired.