Take all your ingredients except for the sugar and basil extract and blend them until smooth in a blender. Add in your sugar to taste. You'll probably use anywhere between 2-4 tablespoons, but it depends on how sweet your strawberries are to begin with. Once your soup is the desired level of sweetness, add in 1/4 teaspoon of basil extract, then add more as needed. If you want to use fresh basil, start with a few chopped leaves and adjust to taste. Place your soup in the refrigerator to chill overnight or for about 8 hours before serving. For the croutons, cut 1"; thick slices of angel food cake and then cut into 1"; squares. Place on an oiled baking sheet and place in a 400° oven until the edges are golden brown (about 7 minutes or so). Place the croutons on your soup right before eating.