In a large saucepan, bring unpeeled potatoes and enough cold water to cover to a boil over high heat. Reduce heat, cover and simmer potatoes until just cooked, about 20 minutes. Drain potatoes, let cool and then refrigerate for at least 1 hour, until cold.

Meanwhile, pulse smoked salmon and lemon peel in a food processor, scraping down bowl. Add sour cream and process until combined. Refrigerate, covered, until ready to serve.

Preheat oven to 425°F. Lightly grease 32 mini-muffin-tin cups. Peel and coarsely grate potatoes. Gently toss potatoes with salt and pepper in a bowl. Place about 1 heaping Tbsp. potato mixture into each muffin cup and press against bottom and up sides, allowing some mixture to extend above rim. (Do not spread mixture too thin or holes will form while baking.)

Bake potato nests until edges are dark golden, about 25 minutes. Coowwl nests in pans for 10 minutes. Carefully remove nests from pans and place on a baking sheet lined with paper towels to set. (Nests may be made up to 4 hours ahead; leave at room temperature.)

Preheat oven to 375°F. Place potato nests on a clean, large baking sheet and bake until heated through and crisp, 6 to 8 minutes. Transfer potato nests to a platter. Using a small spoon, dollop about 1 tsp. sour cream mixture into each potato nest and top each with a tiny strip of smoked salmon and, if desired, a parsley leaf. Serve right away.