Put the water and a knob of butter in a pan and bring to the boil. Add the cornmeal, stir well and let it simmer while stirring. Turn off the heat, add the parmesan cheese and some pepper and let cool briefly.
Butter and flour the tart tins and press a layer of cooked cornmeal into each tin. Place in a preheated oven at 185°C and bake for 10 minutes.
Peel and finely chop the red onion. Heat a dash of olive oil and fry the red onion until soft and caramelised.
Cut the slices of dried ham into strips. Halve the cherry tomatoes.
Cover the tarts with red onion, cherry tomatoes, dried ham and crumble the goat cheese.
Put in the oven again at 185°C for 15 minutes. Allow to cool briefly and garnish with basil.