Preheat your oven to 375 F.
In a saucepan, saute the diced onion on medium heat in 1 tbsp of olive oil until translucent, for about 5 minutes.
Toss in the crushed garlic and stir on a low flame for 1-2 minutes.
Remove from heat and place the onion and garlic mixture into a bowl with the lentils. Using a fork or masher, mash the lentils until a paste forms. You can leave some lentils in pieces.
Add in the breadcrumbs, flax egg, tomato paste, soy sauce, and spices. Mix well until a dough forms.
Scoop about 1 1/2 tbsp worth of dough into the palm of your hands and form into balls. Layer them on a parchment lined baking sheet. Your mixture should be easy to roll and not too wet. If it is, add 1-2 more tbsp of breadcrumbs.
Spray the meatballs with cooking spray, and bake for 25 minutes- flip each one halfway through.
While that bakes, prepare your favorite pasta to serve with.
Once the meatballs are done, serve over your pasta with marinara sauce, and top with nutritional yeast or parmesan!
Leftovers can be kept refrigerated for up to 1 week, or frozen for up to 2 months.