The United States is one of the world's largest sour cherry producers, and almost the entire crop, grown mainly in Michigan, is used for processed cherry products, including channed cherries, cherry pie filling, frozen loose cherries, dried cherries, cherry juice, and cherry brandy.
Fresh sour cherries are a visual feast. If you're lucky enough to find them at the market, you'll see vibrant fire-engine red fruits, with yellow interior flesh. Sour cherries are smaller than their sweet cousins, with a moderately acidic flavor and firmer texture. Too tart to be eaten out of hand, they're traditionally used in pies, tarts, cakes, cordials, confections, and jams, as well as slighly sweetened sauces for poultry. Look for them in late June and July, a few weeks after sweet cherries have reached the market.
At the market, choose sour cherries that are soft and juicy, like ripe plums. Their thin skins are extremely fragile, so you may see a few bruises. Handle the fruits as you would delicated raspberries and refrigerate them as soon as you get them home. Montmorency is the most common variety.
Sour cherries taste best when cooked. The heat turns their plump and tender skins creamy and develops their flavor—intense and fresh, with just a little acidity.
Treat all cherries with the same like touch you give to berries. Keep them refrigerated for up to five days uncovered, rather than in a sealed plastic bag.
If you're lucky enough to have more sour cherries than you can use in a few days' time, freeze the extra; it's the best way to hold them. Freeze fruits in a single layer for three or four hours, and then seal the frozen cherries in doubled zip-top bags. Stash them in the freezer to enjoy year-round.