Draw a large bean shape with a slightly flattened top and bottom
Make one side a little more curved than the other
Add a small inward notch on the inner edge near the top
Refine the outline so it looks smooth and rounded
Draw a smaller curved shape inside near the notch for the renal hilum
Add a thin tube extending from the inner notch for the ureter
Sketch a few short branching lines inside if you want to show internal structure
Trace the final outline with a darker line
Erase any extra sketch marks
Shade lightly to give the kidney a three-dimensional look