Sauté onion over medium heat. Use a tablespoon of water to keep the onion from burning. Cook for 5 minutes until softened.
Add the garlic and sage to the pan and add the remaining water. Cook until the liquid is absorbed. About 2 – 3 minutes longer.
Preheat oven to 375 degrees.
In a food processor, first process the oats until you have a powder. Add the baking powder, salt, pepper, walnuts, and pumpkin. Add onion, garlic, and sage mixture.
Process until well combined.
Shape the mixture into 1-1/2-inch balls and place on a baking sheet lined with parchment paper.
Bake for 15 minutes or until firm and golden brown.
Serve with the aioli or tahini dipping sauce.