Prepare the jicama rounds: Peel the jicama with a sharp knife or vegetable peeler. Using a sharp chef’s knife or mandoline set to about 1/8"–1/4" (3–6 mm), slice the jicama crosswise into 16 even rounds. Pat the rounds dry with a paper towel to remove excess surface moisture. Lay them out in a single layer on a serving platter or cutting board.

Make the avocado spread: Halve the avocado, remove the pit, and scoop the flesh into a small bowl. Add 1 tbsp fresh lemon juice, 1/4 tsp sea salt, 1/8–1/4 tsp freshly ground black pepper (to taste), and 1 tsp olive oil (optional for silkiness). Mash with a fork until mostly smooth but slightly chunky — you want a spreadable texture.

Portion the smoked salmon: If the smoked salmon slices are large, cut them into 16 bite-sized pieces (about 14 g/0.5 oz each). This gives 1 piece per jicama round.

Assemble the rounds: Using a small spoon or a piping bag fitted with a wide tip, place about 1 rounded teaspoon (≈10–12 g) of the avocado mixture onto each jicama round and gently spread to the edges, leaving a small border. Top each with one piece of smoked salmon.

Garnish: Top each assembled round with a thin slice of radish and a small sprig or pinch of chopped dill. Lightly season each finished round with a tiny pinch of sea salt (if desired) and a few grinds of black pepper. If you like, finish with a tiny drizzle (about 1/4 tsp total spread across all rounds) of olive oil and a few drops more lemon juice for brightness.

Serve and store: Serve immediately at room temperature as an appetizer or snack. If you need to prepare ahead, assemble the avocado on the jicama and keep the salmon and garnishes separate; assemble within 30 minutes of serving to avoid the jicama drawing moisture from the avocado. Stored refrigerated in an airtight container, leftover assembled rounds are best eaten within 24 hours; the avocado may brown slightly.