Frittata with Ricotta Cheese and Roasted Peppers (Frittata con Ricotta e Peperoni)

Ingredients

• 1⁄2 cup grated pecorino
• 2 tbsp. roughly chopped flat-leaf parsley leaves
• 1 1⁄2 tsp. kosher salt
• 1 tsp. chopped fresh oregano
• 8 eggs, beaten
• Freshly ground black pepper, to taste
• 3 tbsp. extra-virgin olive oil
• 1 large yellow onion, halved and thinly sliced
• 1 small waxy potato, peeled and sliced into 1/8" rounds
• 1 red bell pepper, roasted, peeled, and cut into 1/4" strips
• 3⁄4 cup homemade or store-bought ricotta