Combine the flour and the yeast in the bowl of a stand mixer. Add the water, salt and 1 tablespoon of olive and mix until combined. Knead for a few minutes until smooth, then transfer to an oiled bowl. Cover and let rise until doubled.

Line a baking sheet with parchment paper. Shape the dough into 4 equal rolls and set on the baking sheet. Brush the tops with olive oil, then sprinkle with sea salt. Let the balls sit for 30 minutes.

Preheat the oven to 400ºF. Bake the rolls until golden brown, 15 minutes. Let cool completely.

Combine the beef with 1/2 teaspoon salt and 1/4 teaspoon pepper. Form the mixture into 4 equal sized patties and indent the centers.

Preheat the oven to 350ºF. Heat a cast iron skillet with a little bit of olive oil. Sear the patties on both sides, then transfer the skillet to the oven to finish cooking, about 8 minutes.

Meanwhile, rinse the arugula. Season with olive oil, 2 tablespoons of the balsamic vinegar, salt and pepper.

Rinse, core, and slice the tomatoes.

In a small bowl, combine the mayonnaise and the remaining 2 tablespoons of balsamic.

Cut the rolls in half. Lightly toast them. Spread the mayonnaise on the bottom half of the buns. Top with some of the arugula, tomato slices, then a burger patty. Top the burger with 2 slices of mozzarella, then 1 tablespoon of pesto. Top with the top burger and serve immediately.