To prepare vinaigrette, combine first 5 ingredients in a small bowl, stirring well with a whisk. Reserve 1 tablespoon vinaigrette. Refrigerate remaining vinaigrette in an airtight container for up to 1 week.
To prepare salad, combine greens, prosciutto, peaches, and tomatoes; sprinkle with almonds and blue cheese. Add 1 tablespoon vinaigrette; toss well.
Top Tips for Tossing Sprinkle Lightly: Crumbly cheeses (100 calories per ounce), chopped nuts (50 calories per tablespoon), bacon (25 calories per slice), and dried fruits (25 calories per tablespoon) are tasty but calorie-dense. Add these at the end. Plate It: Serve your salad on a plate to keep all those tasty (and heavy) toppings from collecting in the bottom, as they might in a bowl. Dress with Less: A little of our dressing goes a long way. Start with 1 tablespoon; toss well. If the greens still seem dry, add more 1 teaspoon at a time.