I like to do this too ... I'll use red onion skins, or spinach leaves, or berry juice, for different colors. I add vinegar, because the kits in my childhood always called for that, and it does help the color stick, and keeps red and blue colors from going brown. I don't get PAAS(TM) saturated colors, just a suggestion of color, the onion peels work the best, like above. Still, kinda fun. Served with salted roe, instead of salt, for the grownups to eat.