These bite-size purple-potato apps fit right in with a reception palette of lavender and goldenrod.
Place potatoes in a pot and cover with at least 2 inches of water. Bring to a boil over high heat. Season generously with salt. Reduce heat and simmer until potatoes are cooked through and easily pierced with a knife, 10 to 12 minutes. Transfer potatoes to a bowl of ice water and let stand until cold. Dry potatoes and slice into 1/4-inch-thick rounds.
Bring 1/4 inch of water to a simmer in a large nonstick skillet over medium-high heat. Stir in vinegar. Crack an egg into a small bowl and gently pour off and discard any runny, loose whites, leaving only the yolk and firm white egg sac in the bowl. Gently pour egg into simmering water and cook just until white is opaque and set but yolk is still loose, 1 to 2 minutes. Repeat with remaining eggs. Transfer poached eggs to a platter or baking sheet sprinkled with water and trim any shaggy ends.
Stir together mayonnaise and mustard until combined. Season potato rounds with salt. Dollop each with 1/4 teaspoon mayonnaise mixture and top with an egg. Garnish with blossoms and serve immediately.