Finely slice the cabbage; a mandolin slicer works great and shreds your cabbage really finely, but it can definitely be done by hand using a sharp chef's knife. Place cabbage in a salad bowl.
Cut avocado in half, use a spoon to scoop out the good stuff and discard the skin and pit. Dice avocado and place it over the cabbage.
Combine all dressing ingredients: 3 Tbsp chopped dill, 3-4 Tbsp fresh parsley, 3 Tbsp oil, 1/2 cup fresh squeezed OJ, 2 Tbsp fresh squeezed lemon juice, 3/4 tsp salt, 1/4 tsp pepper. Just before serving, stir everything to combine.