Stir together first 3 ingredients in a small bowl until smooth. Stir in corn kernels. Drop mixture by 1/4 cupfuls for each cornmeal cake onto a hot, lightly greased griddle or large nonstick skillet. Cook over medium heat 3 to 4 minutes on each side or until golden.
Divide coleslaw among cornmeal cakes; layer with chicken, barbecue sauce, and avocado slices.