01 -
Drain the blueberries using a fine mesh strainer over a large measuring cup. Add tap water to the collected syrup until the total liquid volume reaches 4 cups.
02 -
Pour the liquid mixture into a medium saucepan and bring to a gentle simmer over medium heat. Remove from heat and stir in the strawberry gelatin mix until fully dissolved and smooth, about 1 to 2 minutes.
03 -
Place several ice cubes and water in a large bowl to create an ice bath. Set the bowl with the gelatin mixture into the ice bath and stir every few minutes until the gelatin reaches a lightly gelled state, approximately 30 minutes or when the temperature is around 45 to 55°F.
04 -
Remove the gelatin bowl from the ice bath. Stir in the sour cream and blueberries until the mixture is smooth with some white streaks remaining acceptable.
05 -
Pour the combined mixture into a 10 1/2-cup mold or bundt pan. Tap gently on the countertop to ensure even distribution, cover with plastic wrap, and refrigerate for at least 8 hours or overnight until set.
06 -
Dip the mold into warm water for about 10 seconds, remove, place a serving plate on top, and invert to release the gelatin. Repeat dipping if necessary, and optionally use a small offset spatula or butter knife to loosen the edges if it resists unmolding.
07 -
Slice the gelatin mold with a cake server and transfer slices to plates. Serve immediately. Refrigerate leftovers tightly wrapped for up to 3 days.