Using a small skillet (I used an 8-inch nonstick skillet) cook the soyrizo in a tablespoon or two of olive oil for five minutes. Remove from pan and set aside.
Add another tablespoon of oil to the same pan followed by the potatoes. Add a splash of water to the pan (one or two tablespoons), cover with a lid and cook over medium heat until the potatoes are tender, four to five minutes.
Add the onions to the pan (don't remove the potatoes), season with salt, pepper, onion powder and garlic powder. Cook for three to four minutes, stirring occasionally, just until the onions and potatoes begin to brown. Add the soyrizo (and parsley if using) and stir. Transfer the cooked mixture to a bowl and let cool for a few minutes.
Add the slightly cooled soyrizo mixture to the bowl of whisked eggs. Stir to combine. Pour the egg/soyrizo mixture into the same skillet and cook over medium to medium low heat for five to seven minutes. When the omelette is mostly set with the top portion still runny, cook it under a broiler for about two minutes until the top has set. Alternatively, you can skip the broiler and cover the skillet with a lid and cook on low for a few minutes until the top is set.