Cut potatoes in half and toss with olive oil.
Place cut side down on a baking sheet.
Bake potatoes until just tender, about 25 minutes.
Combine salmon, sour cream, onion capers, and horseradish in a small mixing bowl. Season to taste with pepper.
Cut a thin slice off rounded end of potato and place upright. Scoop a small amount amount out of center of each potato. Spoon about 1 tsp of filling into each potato. Garnish with a small piece of salmon and chives if desired.
Makes 24 appetizers, prep time 15 minutes, baking time 25 minutes.