Heat the olive oil in a large frying pan over medium heat. Add the onions and saute for roughly 5 minutes. Then add the mushrooms and turn the heat up to high and cook for 10 - 15 minutes. The water should be evaporated from the mushrooms after 10 minutes and then the mushrooms should brown for 5 minutes. Remove from the heat and allow to cool down.
Add the oats to your food processor and pulse until fine. Mix the flax meal with 5 tablespoons of water and allow to set for 5 minutes.
Add the mushroom and onions to the food processor along with the rest of the meatball ingredients and process until your desired texture. Cover and store in the fridge for at least 1 hour. This allows the flavors to intensify and the meatballs will stick together better too.
When you're ready to make the meatballs, measure out roughly a tablespoon of the mixture and form small balls. Repeat until the mixture is finished.
Heat up oil in a large frying pan on medium heat. Fry the balls until they turn brown on the underside and rotate. You can also bake them in a 400 F/ 200° C oven for 15 minutes.
Serve with our tomato pasta sauce over some spaghetti or as delicious appetizers at your next party. Enjoy!