Combine apricots, water, and 1 cup of the apple juice in a saucepan. Bring to a boil, lower heat, and simmer, covered, about 20 minutes.
Remove from heat and pour the liquid remaining in the pot into a measuring cup and add enough apple juice to equal 2½ cups fruit juice.
Place the cooked fruit, fruit juice, and tahini in a blender and puree.
Return to pot and add the salt and lemon juice.
Dissolve the kuzu in 3 Tbsp cold water, add to pot, and bring to a simmer over medium heat while stirring constantly. Simmer over low heat for 1-2 minutes, then pour into custard cups or prebaked and cooled tart shells.