Bubble and Squeak

Katie informs me that (normal) Americans don't eat bubble and squeak. I cannot believe it! What do you do with your leftover greens? Pff. I know, people always make fun of English cooking and yes, it is true that my parents tend to eat bland, overcooked vegetables; but I really. Really. Love. Bubble and squeak.

2 cups cooked, shredded Cabbage
1 Onion sliced or chopped
1 lb Potatoes
3 tbs Butter
salt and pepper to taste
oil

1. Peel, boil, and mash potatoes with butter. (Do not add milk.) Season with salt and pepper.
2. Usually we use leftover cabbage for this, but if you aren't: cook in water and 1 tbs butter until tender. Mix together with potato.
3. In a skillet, heat some oil and add the onion, cooking until soft. Add the potato and cabbage mixture and press down atop cooked onions to form a flat cake.
4. Cook over medium heat until browned on the bottom, for about 15 minutes. Transfer upside down onto a plate and heat another 2 tbs (approximately) of oil. Replace cake in the skillet and brown on the other side.

Transfer to plate again, cut into wedges, and serve.