Earthy beets and sweet berries are a lovely match. Roasting the berries softens them and concentrates their flavor, so they taste like strawberries intensified by a factor of 10.
Preheat oven to 375°F.
Place beets on a large piece of heavy-duty aluminum foil; wrap tightly. Bake at 375°F for 1 hour to 1 hour and 15 minutes or until tender. Cool slightly; rub off skins with a paper towel. Cut beets into wedges.
Line a small baking sheet with parchment paper. Place strawberries in an even layer on prepared baking sheet; sprinkle with sugar, and toss gently to coat. Bake at 375°F for 15 minutes. Remove from oven; transfer strawberries to a plate to cool.
Combine oil, vinegar, mustard, salt, and pepper in a jar or bowl; shake or whisk until emulsified.
Divide lettuces evenly among 4 plates; top with beets, strawberries, prosciutto, cheese, and almonds. Drizzle evenly with vinaigrette.