steak sandwiches with roasted tomato and caramelized onions... 1 hour and 30 minutes

Let me just say these are horrible pictures of a really fantastic sandwich... I must have been too hungry to care!

 the goods:

caramelized onions:
1 sweet onion (vidalia)
1 tablespoon butter
1 tablespoon olive oil
1/2 teaspoon salt
1 tablespoon balsamic vinegar

roasted tomatoes:
4 roma tomatoes, halved
1 tablespoon olive oil
2 tablespoons balsamic vinegar
1 teaspoon salt
1 teaspoon black pepper

everything else:
1 flank steak
4 slices white cheddar cheese
pesto
4 brioche buns

Remove the tip and root ends of the onion, cut in half, peel, and thinly slice. In a large cast-iron skillet over medium heat melt the butter and ass the olive oil. Add the sliced onion to the pan and stir to coat. Cook over medium heat until the onions start to soften and brown slightly, stirring occasionally. Reduce the heat to medium-low and continue to saute the onions, stirring them every 5-10 minutes, scraping up the browned bite off the bottom of the pan with a wooden spoon. Continue cooking for 30 minutes more, stirring occasionally. Add the balsamic and continue cooking for another 10 minutes. Remove from the pan and place in a bowl.

While the onions are cooking, preheat the oven to 325 degrees and line a rimmed baking sheet with parchment paper. Place the tomatoes in a bowl and toss with olive oil, balsamic vinegar, salt, and pepper. Place them skin-side-down on the baking sheet and roast for 40 minutes. Allow to cool.

Season steak generously with salt and pepper. Grill the steak about 7 minutes per side. Transfer to a cutting board, tent with foil and allow to rest for 15 minutes before thinly slicing against the grain.

Lightly butter the inside of the brioche buns and toast on the grill for about a minute, watch closely! Spread pesto on each bun, top with steak, cheese, onions, tomatoes, and a bun!