I spent several years in a country that has plantains as a staple in their diet.
Platano frito: If your plantain is green (and I mean green), peel it and slice into about 1 inch pieces. Use about 1/4 inch of oil and fry till lightly browed and somewhat soft. Then squish the piece to about 1/4 inch with a piece of wood and refry till crispy, add salt to taste. These are a great replacement for french fries.
You can also slice thin like a potato chip and fry. Make sure you salt right after cooking so the salt sticks.
Mangoo:Another way with green plantains is to peel, cut into chunks and boil till soft but not mushy. When done, strain and mash leaving some big bits for texture. Add a little vinegar (1tsp) and some sautéed onions. This is nice with fried eggs at breakfast.
Bake like a potato in the oven with the skin on. When done peel and serve.
Maduro:If your plantain is ripe, peel, cut in half and slice lengthwise into 1/4 inch strips. Fry in med-hot oil till the sugars caramelize and serve as an accompaniment with rice dishes.
I know several more but I'm done typing for now
