Bad Piggies Rise and Swine Level 2-23 can be 3-starred in two steps. First guide Freckles to the finish line through the ravine on the left. A simple frame without wheels powered by a soda bottle should be enough. Then build a three frame cart on wheels with a soda bottle facing backward. Let it roll down the hill, and use the soda to slow it down to collect the star below.
If you have a different strategy for completing this level feel free to leave a comment below.