Slice the potatoes into 1/2-inch thick wedges. Place in large bowl with olive oil, vinegar salt, pepper, and cayenne pepper. Toss to coat. Transfer to a baking sheet and bake for 30 minutes until potatoes are crisp and tender on the inside.
In a large pot or fryer heat canola oil to 350 degrees F.
In a large bowl combine baking powder, cayenne, paprika, and 2 cups flour. Season with salt and pepper. Whisk in buttermilk and club soda. Dredge the tilapia in the remaining 1/2 cup flour then dip into batter. Carefully drop into the hot oil. Fry in batches for 5 minutes until golden brown and remove to a plate lined with paper towels.