. In saucepan of boiling water, cook potatoes for 8 - 10 minutes; drain and let cool. I am told by the true master roesti makers to let the potatoes sit overnight in the fridge. Grate into a bowl. Sprinkle with 1/4 tsp each salt and pepper; toss gently.
2. In separate bowl, stir together cheese, zucchini, corn, basil and a pinch each of salt and pepper.
3. In a 9-inch nonstick skillet, heat half of the oil over medium heat, swirling to coat pan. Add half of the potatoes; pat to spread evenly. Spread with cheese mixture, leaving border uncovered. Top with remaining potatoes, patting down and pressing edge to seal. Cook for about 12 minutes or until bottom is golden and crusty.
4. Using a wooden spatula and shaking pan gently, loosen roesti from pan. Invert flat plate on skillet. Using oven mitts and holding plate and skillet together, invert roesti onto plate. Return skillet to heat; adding remaining oil, swirling to coat pan. Slide roesti back into skillet, browned side up; cook for about 10 minutes longer or until bottom is golden and crusty.