Heat olive oil in a 10-inch skillet over medium-high heat. Add onions and cook 4 to 6 minutes or until tender.
Whisk together eggs, cream cheese, salt and pepper.
Add eggs to the pan and cook 3 to 4 minutes or until just set in the center, tilting the skillet and lifting the edges of omelet with a spatula to let uncooked portion run out to edges.
Sprinkle with chives and capers and lay salmon over half of the omelet. Using a spatula, fold the omelet half, without the salmon, over the half with salmon to enclose it, and slide the omelet onto a plate.
Cut in half crosswise and serve with matzah and cream cheese or an open faced bagel with cream cheese.