For perfect apple cubes: Stand the apple on your cutting board and cut down into four slabs; discard the core. Lay slabs, cut sides down, and cut into 1/2-inch slices, then crosswise into 1/2-inch cubes.
Chili-spiced onion rings get really crisp when shallow-fried. And there's no need for special equipment or a ton of oil, like you would need for deep-frying.