3 Italian sausages (about 360 grams total, mild or spicy as you like)
2 1/2 cups peeled and diced Yukon gold potatoes (about 2 medium potatoes)
1 cup diced cooking onion (about 1 medium onion)
10 large eggs
1/4 cup chopped flat-leaf parsley
1 1/2 teaspoons kosher salt
1/4 teaspoon freshly ground black peppercorns
Vegetable oil, for cooking
1/2 cup flavor bomb cherry tomatoes, halved
1 1/4 cups baby arugula
1 teaspoon extra virgin olive oil
Additional kosher salt and black peppercorn to taste
Preheat oven to 350 degrees Fahrenheit.
Heat 12-inch cast iron or oven-safe non-stick skillet over medium high heat. Add 1 tablespoon vegetable oil to pan. Remove casing from sausages (discard casing), and roughly crumble into hot pan. Fry sausage pieces until golden brown and cooked. Remove from pan and set aside.
Add onions to hot pan and cook until light golden and soft, about four to five minutes. Remove from pan and set aside with cooked sausage. Add two tablespoons oil to pan and cook diced potatoes until golden brown and mostly cooked through, about five to six minutes. Season potatoes with 3/4 teaspoon salt. (If bottom of pan has a lot of stuck on browned bits, remove potatoes and give the pan a quick good wipe before continuing on with adding back 1 tablespoon of oil and browned potatoes.) Add sausage and onion back to pan and stir to distribute evenly.
In a large bowl, whisk together eggs, chopped parsley, 3/4 teaspoon salt and 1/4 teaspoon pepper. Pour egg mixture into pan, now over medium heat and allow egg to run over filling. With a spatula, lift edges slightly to allow egg to run under.
Let egg mixture cook on the stovetop about two to three minutes, to allow bottom to set before placing the pan into preheated oven to finish cooking. Bake in oven about 20 minutes, until center of frittata is set. Remove from oven and allow frittata to cool 15 minutes in the pan before serving.
Just before serving, in a medium bowl, toss together halved tomatoes, arugula, extra virgin olive oil, salt and pepper to taste. Arranged dressed salad on top of the frittata and serve straight from the pan.