hmmm. I'd use the highest concentration of alcohol that you can find. Vodka would be too weak, I'd say 70% Iso would be too. My solvent of choice is methanol. It's supposedly the best solvent for retrieving as much of the alkaloids as possible. You can get it in the paint section of most hardware stores, sometimes it's labeled as "Methyl Hydrate", It's always sold 99.9% pure in that form. When using methanol just make sure it's all evaporated from the residue, it's a poison. Just make sure it's all evaporated and you're fine. If you can't find methanol use Isopropanol from the drug store around here you can get 99% Iso or 99% denatured ethanol. Any 3 of those will work fine, just make sure it's well evaporated.
After it's evaporated I scrape up the tar and put it into toilet paper "parachutes" and swallow them that way. Much nicer than having it come in contact with the inside of your mouth and the horrid taste sensation that results from that.