Rinse and cut the eggplant into medium-thick round slices (between 1/2 and 1 cm)
Steam them for about 15 minutes (check with the tip of a knife). You can also cook the aubergine in a pan or in the oven if you prefer.
Meanwhile, cut the onion into strips and fry in a little olive oil for less than 10 minutes, until the onion is melting. At the end of the cooking time, you can add the slices of cooked aubergine 2/3 for grilling (optional).
Place pieces of cheese on the bread slices (or brush the bread if using stracciatella or ricotta) .
Arrange a few slices of eggplant on top of the cheese.
Add strips of red onion.
Season with oregano, pepper and salt.
Bake in the oven for 5 to 7 minutes at 180C.
Leave to cool for a few moments, then add the beans to the toast and serve immediately!