Roast the capsicum on open fire until the skin is completely black.
Transfer the capsicum into a bowl, add some garlic and thyme and a drizzle of olive oil and allow to cool to room temperature. Once cold enough, remove the skin from the capsicum and slice them in strips. Season with balsamic vinegar, salt, pepper, olive oil and roughly chopped parsley leaves.
Toast the bread on both sides, spread a generous amount of the onion relish on each slice.
Place the capsicum on one side of the bread, and finish with 3 slices of Prosciutto and a drizzle of olive oil and some more optional balsamic vinegar.
Finish with the second slice of bread and serve.
Additionally, you could add a few slices of goat cheese to elevate the taste of the sandwich.