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This drink is one of my all-time favorites. It definitely needs a good, natural grapefruit soda -- Fresca, as much as I like it, won't do (esp. artificially sweetened as we get it here in America). Ting works great if you have any trouble finding Jarritos.

As for the tequila, I'll disagree a bit with Paul here. For drinks like a Margarita, 100% agave is a must. For this one, seeing as how you're mixing with a very sweet soft drink, I don't think it's necessarily required. A good quality "mixto" like El Jimador (made by Herradura) works great and is in fact the way Palomas are usually made in Mexico. If you want to use a 100% agave don't let me stop you, but honestly this ain't the place for anything remotely expensive.

Finally, as Anita over at Married...with Dinner notes, a nice big dash or two of Fee Bros. Grapefruit Bitters really brightens it up. I also like to add the salt at the very end, sprinkling it over the ice at the top of the finished drink.

Cheers!

Tried it with fresca over the weekend and did not like it at all. But I did not add fresh lime juice and I think that would have made a big difference. Trader Joe's makes a good grapefruit Italian soda - might be good in this recipe.

Dunno about Fresca, but the improbable combination of Squirt and Rose's Lime juice actually works quite well: 3 shots Tequila, 1 shot Rose's and 1 12-ounce can of Squirt. Pucker up!