Why Bach omitted a slow, second movement in his Brandenburg Concerto No 3 in G is not known. Usually a short cadenza is played, often by the principal violinist, violist or continuo player. Sometimes a slow movement from another of Bach's works is inserted. 

Here is a small offering suggesting a solution to this unsolvable riddle, written in the relative minor of the home key. It has no programme. It was originally written as a compositional exercise in Christchurch, New Zealand in 2006, and had an amateur performance there with the Christchurch Camerata. The piece was revised in 2020.