Combine cream cheese, yogurt, garlic, 1/4 cup basil leaves, and next 4 ingredients in a food processor; process until smooth.
Spread 1 tablespoon cream cheese mixture on 1 side of each slice of bread. Top 4 slices evenly with tomatoes, remaining basil leaves, salmon, and onion. Top with remaining bread slices. Serve immediately.
Wine note: "The red onion has a leading role in combination with smoked salmon. This recipe beckons Rodney Strong, Chalk Hill Chardonnay 2002 ($16)--a full-blown, refined, and elegant wine. Rich and complex with flavors of vanilla, green apple, pear, and pineapple, the wine is balanced by firm acidity, toasty oak, and very buttery undertones." --Rosalind Johnson, Divas Uncorked, Massachusetts