Combine the walnuts and mushrooms in a high speed food processor and pulse several times to chop the ingredients to resemble ground beef. Making sure not to chop too fine otherwise the mushroom will become too soft and watery.
Transfer to a mixing bowl.
Heat the oil in a pan and sauté the diced onion until soft.
Next, add the minced garlic and walnut mixture to the pan and continue to sauté for 2-3 minutes.
Combine the remaining ingredients and stir to combine.
Sauté for another 3 minutes to cook completely.
Adjust seasoning to taste.
Serve and enjoy.