Spanish-Style Tortilla with Salami and Potatoes

Heat oven to 400 °F. Cook the salami in a large oven-safe nonstick skillet over medium heat until beginning to brown, about 1 minute per side; transfer to a plate. Add the onion, potatoes, 1 Tbsp of the oil, 1/2 tsp salt and 1/4 tsp pepper to the skillet and cook, stirring occasionally, until the potatoes are golden brown and just tender, 10 to 12 minutes; stir in the chopped parsley and salami. Whisk together the eggs and cheese, pour into the skillet and stir to distribute the ingredients. Transfer the skillet to the oven and bake until the tortilla is puffed, brown around the edges and a knife inserted in the center comes out clean, 10 to 12 minutes. Meanwhile, in a medium bowl, whisk together the vinegar, mustard, remaining 2 Tbsp oil, and 1/4 tsp each salt and pepper. Add the tomatoes and toss to coat; fold in the parsley leaves. Serve with the tortilla.