Heat up the oil in a pan to medium heat, add the onion and stir until they begint o soften. Add the garlic and stir. Cook for 2-3 mins.
Add the celery, carrot, dried herbs and mix, let it cook for 5 mins.
Add the sliced mushrooms and let it cook for another 5 mins.
Using a food processor or hand blender, blend the sautéed vegetables with the other ingredients, until you get a chunky-like texture. Place in a bowl, flatten the surface of the dough and let it rest in the fridge for 20-30 mins. Preheat the oven to 180ºC.
Shape the dough into balls, place them on a baking tray covered with baking paper. Bake them for 30-35 mins at 180ºC, flipping them after 20 mins to allow even cooking. You can bake them all or freeze some of the meetballs for some other time!
Serve along with a sauce, along with pasta or rice.
If cooked - leave in the fridge for up to 3-4 days.
If frozen - place in a bag and consume within 3 months. Remember to bake them like mentioned above.