A great British tradition [still seen in cafes] is liver'n'bacon.
Rinse and pat dry your liver and thinly slice, meanwhile get some onions and spices sauteing and start to cook the bacon. You'll want your cooking oil of choice at a relatively high heat as the best way to do liver is to flash fry it.
When the bacon's done to your desired level, throw the liver in and keep moving. It should take no more than two minutes to be done, and flash frying should avoid the chewy texture I remember from childhood. Serve with whatever greenery you choose. Melt butter on top. Enjoy!
Now if someone wants to do a paleo version of another childhood memory - steak and kidney pie - I'd me eternally grateful :)