The instructions here are approximate because this is not an exact science here. You can adjust proportions to your taste.
Olive, canola, or grape seed oil
2 medium onions, finely slivered
2 lbs sliced mushrooms (I use cremini and like to slice them myself – they stay more fresh and moist this way)
1-2 tsp salt
Heat a few glugs of oil over medium heat in a pan and add the onions when oil is hot and is beginning to sizzle a bit.
Sauté the onions until they are translucent and begin to change to pale golden color. At this point, add the mushroom and sauté over medium heat until the mushrooms turn deep brown and reduce in size by about half. Make sure that nothing gets burned and too brown (or it’ll turn bitter) so please be careful to regularly stir and, if necessary, reduce heat to low.
When it has cooked down substantially, add 1 tsp of salt and mix well – taste to see if you need more salt and add more if needed. Otherwise, remove from heat and pulse in a food processor until the consistency of pâté.
Serve warm or chilled – it works equally well in either state.