Add the avocado oil to a non-stick skillet and heat to medium-high. Add the sliced onion and sauté, stirring occasionally, until onion is translucent and begins to brown around the edges, about 5 to 8 minutes.
If at any point it looks like the onion is burning around the edges, either add a small amount of additional avocado oil, and/or add about ¼ cup of water or broth to deglaze the pan.