- Slowly sauté the onion in the grease or butter until soft. Then turn up the heat and add the livers. Cook until done, allowing it to brown a little. Add a pinch or two of salt.
- Turn heat to high and pour in half the bourbon. Allow to flame. Set aside to cool completely. Be sure to save any juice in the pan.
- When the livers are absolutely cool, purée them in a food processor for a second, then add the mustard, nutmeg, Tabasco, and lemon juice. Begin to slowly feed in the softened butter.
- Lastly, add the rest of the bourbon and taste for salt. If you used bacon grease it may be salty enough. If you are using livers that have been frozen, they may produce, when sautéed, enough liquid to make the mousse runny. Since it tends to be tasty, I just add a little more butter.
- Serve at room temperature with crackers or toast and olives and pickles.