COOK lentils as the instructions at the package, when they get soft, drain. PREHEAT your oven at 180ºC. Heat the oil in a pan and fry the onion, carrots and celery for 5 minutes, add garlic, and mushrroms, cook until vegetables get tender soft and onion looks transparent. PUT the ingredients in a bowl, add lentils, seasoning, chopped parsley, oats and flour. Add soaked and drained chia, eggs, breadcrumbs, salt and pepper. Stir. WRAP a large oven container with waxed paper, spread the lentils mixture and press to compact. Bake for 25 minutes. TAKE AWAY from the oven, let it cool. TAKE OUT of the container and slice. SERVE at ambient temperature or cold.