On a recent trip to Rome, I had the pleasure of trying the Concord grape sorbet from Fior di Luna and was totally blown away. The sorbet totally captured the full burst of flavor you get when biting into a Concord grape without all the hassle of having to spit out the seeds and skin afterward. I knew I had to try to recreate it at home, and so I adapted this recipe from Gourmet.
Instead of adding the full amount of sugar, I started with 1/4 cup, which ended up being enough for me. Depending on how much purée you end up with and how sweet your grapes are, you'll want to adjust the amount of sugar; it should taste just a little too sweet at room temperature since once it's frozen it'll taste less sweet. To add a little depth to the sorbet I added a pinch of salt and a tablespoon of red wine, which also helps keep the sorbet from getting too icy. —Joy Huang | The Cooking of Joy
Purée half of grapes in a blender until smooth, then force through a fine-mesh sieve into a bowl, discarding solids. (If you have a very powerful blender like a Vitamix, you probably don't want to blend on high since you want the seeds to stay whole.)
Repeat with remaining grapes to yield 2-3 cups purée. (I ended up with a little more than 2 cups.) Whisk in sugar, salt, and red wine. Taste and add more sugar if necessary, just until the mixture is a little too sweet at room temperature. Chill until very cold, 3 to 6 hours.
Freeze in ice cream maker, then transfer to an airtight container and put in freezer to firm up, at least 2 hours.
You can also pour the frozen churned sorbet into popsicle molds to make really awesome Concord grape popsicles!