Run the liver under cold water, pat dry with paper towels, and slice into thin strips.
Heat the olive oil in a large heavy-bottomed skillet (or cast iron pan) to medium heat.
Tip in the sliced onions and minced garlic and cook for 2-3 minutes, ensuring the onions have turned translucent but the garlic isn’t overcooked.
Add the liver to the pan and cook for about 5 minutes or to your liking, turning once to make sure each side is browned.
Season the mixture well with thyme, salt and pepper and if desired, drizzle a little balsamic vinegar on top. Stir to combine and cook for a further 2 minutes, until the vinegar has reduced.
Serve garnished with parsley, along with your favourite side dish.
