Pre-heat oven to 200C.
Put oil in oven dish/pan into the oven to heat up.
Finely chop onion.
Peel carrot and finely grate along with courgette and celery (discard celery fibres).
Place onions, vegetables, mince meats, herbs, garlic, salt and pepper and ground rice crispies into mixing bowl. Get your hands in and give everything a good mix up until well combined.
Make golf ball-sized meatballs, placing onto chopping board on large plate.
Once all meatballs are made, take out the oven dish/pan from the oven. Put the meatballs in dish/pan, pour over tomatoes. Put tray back into the oven for 10-15 minutes until the top of the meatballs start to brown and have shrunk in size a bit. IF you think the sauce needs water, now is the time to add this.
Take out meatballs, turn them over. Sprinkle stock cube through the tomatoes and gently stir, then put back into the oven for another 15mins until meatballs are nicely browned and the sauce is bubbling away nicely.
Take out the meatballs from the oven and check they are cooked to your liking and give the everything a taste test. Season sauce with salt and pepper if you think it needs it.
Bring to the table and watch it disappear.