Ensure the canned pineapple chunks, sliced peaches, and mandarin oranges are drained. Slice all the fruit into bitesize pieces, then mix them together in a large bowl.
Make the fruit sauce by whisking the vanilla pudding mix, milk, orange juice concentrate, and sour cream together until smooth.
Fold the fruit sauce gently into the mixed fruit. Once the sauce has been mixed in, cover the bowl.
Before serving, leave the bowl to chill for up to 3-4 hours.