Place potatoes in a 13 x 9-inch glass or ceramic baking dish, and drizzle with 3 tablespoons water. Cover with foil and bake at 375 for 45 minutes or until tender.
Remove the foil, and cool for 15 minutes. Halve potatoes.
Combine olive oil, vinegar, and mustard in a small bowl, stirring with a whisk. Cook bacon in a large nonstick skillet over medium heat until crisp, stirring occasionally.
Remove bacon from pan using a slotted spoon, reserving drippings in pan. Increase heat to medium-high.
Place potatoes cut sides down in pan; cook for 5 minutes or until golden brown.
Place potatoes in a medium bowl.
Remove and discard roots and outer leaves from ramps; rinse and drain ramps. Pat ramps dry. Thinly slice bulb ends and leaves crosswise to measure 1/2 cup.
Add the ramps, bacon, and radishes to potatoes.
Drizzle dressing over potato mixture, and sprinkle with salt and pepper. Toss.