Heat the oven to 350F.

Line a baking tray with parchment paper.

1. Heat the 3-4 tablespoons vegetable stock in a large pan, add the diced red onion. Sprinkle over 1/2 a teaspoon of kosher salt (if using) and cook on a low heat, stirring occasionally until translucent. You will find they will cook down and reduce in volume.
2. Add the minced garlic and balsamic vinegar and cook for a further 3-4 minutes.
3. Place the cooked rice and lentils in a large bowl, add the sun dried tomatoes, nutritional yeast, Dijon mustard, tamari and olive oil. Stir well to combine.
4. In the bowl of a food processor blitz the oats and toasted pumpkin seeds. Add to the rice mixture along with the sea salt,  freshly ground black pepper and cumin.
5. Heat a couple of tablespoons of vegetable stock in a large pan until hot, add the mushrooms and saute until they release their juices, cook a minute more and add the tablespoon of tamari.
6. Place the mushrooms in the bowl with the rice mixture, add the chopped parsley and combine into patties.
7. You can refrigerate the patties (covered in plastic wrap) until you’re ready to cook them (overnight if necessary).
8. When ready to cook brush them with vegetables stock and place in the oven for 20 minutes, remove from the oven, carefully flip over and bake for a further 10-15 minutes.
9. Place in a toasted burger bun and add any other fixings you desire.