Preheat the oven to 480ºF / 250ºC
Cut the tomato in thick slices and roast in the oven the for a couple of minutes with olive oil, dried oregano, and (if you want) a pinch of sugar until some of the water has evaporated.
Cut avocado into thick slices and if you are using a hard cheese, cut into thick slices as well
Cut the bread slice in half and roast one half on one side in a skillet. The other slice can be roasted on both sides
Build the sandwich. Place the bread slice with the roasted side up. Start with tomato slices, follow with avocado an mozzarella. Repeat so that you have two complete layers. Add salt and pepper to taste.
Grill in the oven until the cheese has melted and got a nice colour.
Take out the sandwich an pour one tablespoon of kale and arugula pesto* on top. Place the second bread slice on top of everything.