Preheat the oven to 400°F (200°C) or as indicated on the package directions if using a store-bought pizza crust.
Peel the onion, cut it in half and then in slices. Wash the fennel (or red pepper) and cut it into very thin strips.
Roll out the pizza dough onto a baking sheet and prick the bottom with a fork. Place it on a baking sheet and bake for 12 minutes (or as indicated on the package).
Heat a large pan or skillet with olive oil. When hot, add the onion and fennel and caramelize over medium-high heat. Stir regularly to prevent them from burning. It should take about 10 minutes until they are cooked and golden brown.
Take the pizza crust out of the oven. Top it with tomato sauce and dried herbs. Add the caramelized vegetables and bake for 5-8 more minutes.
Remove the pizza from the oven, top with some fresh arugula and drizzle with balsamic glaze.