A V-Slicer (mandoline) will chop the potato, bell pepper, and tomato in seconds, and is a lot less expensive than a food processor.
If you prefer crunchier bell peppers, add them halfway through cooking the potatoes. You can also add onions or sautéed onions, and parmesan cheese instead of feta. If you use a harder cheese such as parmesan, add it along with the garlic so that it fries well.
If you can’t serve a dish that doesn’t have meat in it, add some sliced Italian sausage along with the potatoes, and reduce the olive oil.