Heat the oil in a frying pan and gently cook the onion, garlic, carrot and celery together until tender. Sprinkle in the herbs and set aside to cool.
In a bowl mix together the breadcrumbs, mince, egg, cooled cooked vegetables and 1/4 cup tomato sauce.
Grease a 12 cup muffin pan and divide the mixture between the cups, then smooth the tops with the back of a spoon. You can spread a spot of tomato sauce on top of each one with the spoon before placing them into the oven to bake.