Melt butter with olive oil in a large skillet over medium-low heat. Add yellow onion, and cook 20 minutes or until golden. Let cool slightly.
Whisk together sour cream, goat cheese, eggs, and 3/4 teaspoon pepper. Stir in yellow onion and hot-smoked salmon. (If using coldsmoked salmon, do not add at this time.)
Unfold the puff pastry on a parchmentor nonstick foil-lined baking sheet. Roll evenly to remove wrinkles. Fold over edges 1/2 inch, and press lightly to form a raised crust. Sprinkle with remaining 3/4 teaspoon pepper. Spread onion mixture evenly over the pastry, leaving a border of about 1/2 inch. Top with sliced red onion and half of the green onions. Bake at 425° for 20 minutes or until the pastry is golden. (If using cold-smoked salmon, cut into strips, and place on top of tart after baking.) Sprinkle with remaining green onions. Serve warm or at room temperature.
The case for wine: Aside from his duties as CEO and president of Carnival Cruise Lines, Bob Dickinson pursues his passion for wine. Evidence? His wine cellar contains more than 22,000 bottles, making it one of the country's largest private collections. As founder of the Presidential Wine Club, Bob insists that good wine be fun and accessible. Bob's recommendations: J. Lohr Riverstone Chardonnay; Beringer Private Reserve Chardonnay; Kongsgaard Chardonnay.