Berry Delicious Margaritas

Not only are berries in season, but they are on sale at the market! How could I resist coming home with lots of fresh blackberries, raspberries and strawberries.
I accidentally stumbled upon this recipe on Epicurious and knew it was meant to be.
The prep took a bit of work, since the berries must be pureed and strained to remove any seeds. I considered trying to purchase berry juice, but they all included banana and, frankly, a banana margarita does not sound appealing to me. The result was outstanding: extra smooth and very fruity. I used equal parts blackberries and raspberries, but you could tip the scales either way as long as the proportions stay the same. The only problem I had with the original recipe was that it didn't tell me how much puree I would need to make the drinks. I noted how much to look for below. I rimmed the glasses with salt. Sugar could be used instead, but I personally think salt is the way to go.
Serve these at a bbq. You only need these drinks, a bowl of salsa and some chips to start a great party.

Triple Berry Margaritas
2 cups blackberries
2 cups raspberries
1/2 cup fresh lime juice
2/3 cup sugar
1 1/2 cups tequilla
2/3 cup Grand Marnier
2 cups strawberries, frozen but thawed slightly
5 cups ice, divided

Whizz or blend blackberries, raspberries, lime juice and sugar until smooth. Strain through a fine sieve to make about 3 cups of puree. Stir in tequila and Grand Marnier and refrigerate until ready to use, or at least 1 hour.

Combine 1/2 of berry-lime mixture with 1 cup of strawberries and 2 1/2 cups of ice in your blender. Blend until smooth and serve in salt rimmed glasses. Repeat with remainder of berry puree, strawberries and ice.
Serves 8-10.