Step 1 Combine flours, baking powder, cumin, coriander, egg and milk in a large bowl. Whisk until smooth. Stir in corn and onion until combined.
Step 2 Spray a small frying pan with oil and place over medium-high heat. Spoon 1/4 of the corn mixture over base of pan. Cook pancake for 1–2 minutes each side, or until golden and cooked through. Cut into large wedges (or halves).
Step 3 Meanwhile, cook beans in a saucepan of boiling water for 2 minutes, or until tender-crisp. Drain, then rinse under cold running water.
Step 4 Place avocado, rocket, tomato and beans into a large bowl. Toss gently to combine. Serve corn cakes with avocado salad, sour cream and lemon wedges.