i ordered a tequila & tonic at our neighborhood bar recently and the bartender was taken aback. i didn't know it was such a weird thing - maybe years of gin & tonics made me realize that everything is better with tonic. but i think i ended up convincing him that it was actually good.
he in turn informed me that when you are buying tequila, you should at the very least buy one made from 100% agave. this was helpful, because i really don't know anything about tequila and actually rarely drink it. but it always tastes summery when i do, and this drink tastes like liquid summer.
all you need are some raspberries (i used frozen ones, but if you have fresh, obvs use those), some lemon, some agave nectar (or simple syrup or sugar - i just liked the idea of agave plus agave and agave nectar mixes easily into cold drinks, unlike sugar or honey), some tequila, and some tonic!
first, muddle the berries and lemon together. for two tall drinks, i used about 1/4-1/3 cup raspberries and 1/4 of a lemon, rind and all. i just smashed them with a wooden spoon until the berries were mostly smushed and the lemon had been broken down fairly well. it's not like it has to be uniform in texture. then add some agave to taste - it depends on how sweet your berries are, etc. i used about 1 1/2 - 2 teaspoons, maybe.
then divide into two glasses, add whatever amount of tequila you are comfortable with, top the glass off with tonic and lots of ice, and imagine yourself on a beach in cozumel or something.
or, in my case, acknowledge that you are in portland and it is still chilly in june and you need a sweater when you sit outside sipping exotic cocktails.