Season the liver. Don't use too much seasoning because liver incorporates seasoning very easily.
To this stipulated amount you can add a reasonably full tablespoon of seasoning.
Important: Do not use freshly prepared seasoning with raw garlic and salt. Opt for ready-made seasoning purchased in markets. I used non-market and what happened: the liver and hardened.
Fry the liver and set aside.
Cut the onion into thin slices. Season to taste and sauté in the liver broth in the pan.
Cut the tomato to your preference, either slices or pieces. Season to taste.
It can be accompanied by rice and beans, salads and general drinks (juices, soft drinks, etc).