Start by gently placing your fresh blackberries in a large mason jar. In a medium mixing bowl, combine the sugar, distilled water, and vodka, stirring well. Don't worry if the sugar doesn't fully dissolve at this stage - it will break down naturally during the steeping process.

Pour this mixture over the blackberries in your jar and secure the lid tightly. Give the jar a few good shakes to distribute the contents evenly, then place it in a dark, room-temperature location where it won't be disturbed by direct sunlight.

Let the mixture steep for 2-3 months, turning the jar upside down weekly to gently redistribute the ingredients. When ready, strain the mixture through a fine-mesh sieve lined with cheesecloth or a coffee filter into a clean container. Your homemade blackberry liqueur is now ready to enjoy!