Line a small cookie sheet or glass pan with parchment paper.
Spoon out two 5.3 ounch yogurt containers into a thin layer -- keeping the 3rd yogurt set aside. (I like to keep it pretty thin so it's easier to eat, approximately 1/2 cm high).
Stir in the all-natural blue dye to the third yogurt container.
Put a few dollops of the blue yogurt sporadically onto the thin layer of yogurt. Then use a knife to go back and forth and swirl it around.
Adorn the yogurt with blueberries and strawberries (use cut outs for the strawberries if you so choose -- we used a star and then U S A.)
Freeze for at least 4 hours. Then cut into slices. Store leftovers in the freezer.
