3 fennel salad sour dressing Recipes

red potatoes , scrubbed clean, patted dry with paper towel (or white potatoes), olive oil, salt, fresh ground black pepper, fennel bulb, stem removed , fronds reserved, wiped clean, bottom left intact, cut lengthwise into 1/4-inch slices, sweet onion, peeled, ends trimmed , cut lengthwise into 1/4-inch slices, buttermilk, sour cream, apple cider vinegar, hot red pepper sauce (or to taste), chopped scallions (green onions), chopped fresh parsley leaves, chopped fresh dill (1/4-1/2 tsp. dried ), minced fresh garlic, chopped fresh oregano leaves (1/4 tsp. dried ), reserved fennel leaves

sour cream, olive oil, divided, prepared horseradish, chopped fresh dill, white wine vinegar, divided, arugula, sliced fennel bulb, sliced red onion, smoked trout or smoked whitefish, coarsely flaked