Add the vinegar, raspberries, lemon juice, and olive oil to a food processor and blend until smooth. Add salt and taste. Adjust other flavors to achieve the desired balance. Set aside.

Add lettuce, mint, strawberries, blackberries, and toasted almonds to a large bowl and gently toss to combine.

Drizzle with raspberry vinaigrette and serve immediately on chilled salad plates for a refreshing appetizer or light lunch.