vegan stroganoff

My version of a vegan stroganoff, not particularly photogenic but cheap and absolutely delicious
Ingredients:
1 carrot
1 onion
1 stick celery
6 chestnut mushrooms
1 tin green lentils, drained and rinsed
1 tbsp Oatly creme fraiche
Vegan stock made with 2 tsp Marmite and boiling water
1tsp onion gravy granules to thicken
1 tsp mustard
Fresh garlic, chili, parsley, salt and pepper to season
Mashed potatoes to serve.