Preheat the oven to 350°F.
In a skillet, over medium-high, heat the olive oil. Add the onion and cook until it turns a little golden (about 10 minutes).
Add the garlic and mushrooms, and continue cooking for 5 minutes.
Add the lentils to the mushroom mixture, and cook for 3 minutes.
Place the mushroom lentil mix into a bowl and add the rest of the ingredients. Use a spoon to mix everything together.
Line a loaf pan with parchment paper. Be sure to leave the sides of the paper sticking up. Fill the loaf pan with the "meat" mixture.