In a food processor, pur�e the mango and strawberries. You should have about 1 1/2 cups of pur�e. Transfer to a container, cover, and refrigerate until cold — about 1 hour.
In a blender container, combine half the pur�e, half the tequila, half the triple sec and half the lime juice. Fill the jar to the top with ice cubes, cover, and blend on high until thick and slushy. Transfer to a pitcher. Repeat with remaining ingredients. Stir to blend, pour into margarita glasses, and serve immediately.