Heat oil in a 12-inch frying pan or large wok. Add red bell pepper and sauté for a minute or two. Add raisins and sauté for another minute or two. Add garlic and sauté for a minute, until barely golden; do not allow garlic to burn. Add the spinach (it will fill up the pan), sprinkle with salt and pepper and toss just until the spinach is wilted. This will take 2-3 minutes or so.
Stir in cooked rice and feta cheese and heat through, a minute or two. Taste and season with more salt and pepper if you like, turn the heat off, put a lid on the pan and let it sit for a couple of minutes. Serve.
INGREDIENT NOTE: Why use day-old rice? It works better than freshly made rice, which tends to be too gummy for this dish. Day-old rice has grains that are more distinct.