Add 2 cups of sour cherries to a quart-sized canning jar, 1 cup of sugar, and fill the rest of the jar with vodka. Close lid tightly and shake. Shake jar daily for one week, or until sugar dissolves. Let sit for 3-6 months before enjoying. Traditionally, this is made at the cherry harvest in Door County Wisconsin (July) and then the jars are not opened until Christmas. Watch out - because if you eat the cherries after they have been soaking in alcohol for 6 months they are VERY strong!!
Serving size... ? Depends on how you use it. You can sip as a cordial or use it as an ingredient for mixed drinks. I have a friend who adds it to his fruitcake recipe, and I think it would be very good drizzled over vanilla ice cream.