Step 1In a small bowl, stir 1 ¼ cups boiling water into 1 flavor of gelatin until completely dissolved, about 2 minutes. Pour ¾ cup dissolved gelatin into a mold. Refrigerate until set but not firm (the gelatin should stick to the finger when touched), about 15 minutes.
Step 2Refrigerate the remaining gelatin in the bowl until slightly thickened (the consistency of unbeaten egg whites), about 5 minutes. Gradually stir in 3 tablespoons of the sour cream or vanilla yogurt. Spoon this gelatin over the set gelatin in the mold and refrigerate until set but not firm, about 15 minutes.
Step 3Repeat the process with each remaining gelatin flavor, making sure to cool the dissolved gelatin to room temperature before adding to the mold. Refrigerate between each layer until you have 10 alternating clear and creamy gelatin layers. (for more layers, use simply repeat using additional gelatin colors, water and sour cream or vanilla yogurt).