In a small bowl, combine ⅓ cup olive oil, 2 tsp smoked paprika, 2 cloves minced garlic, 1 tsp salt and ½ tsp pepper. Whisk to combine.
Place the steak in a plastic resealable bag and pour in the garlic paprika oil. Massage oil into steak, press out the air in the bag and seal.
Place the steak in the refrigerator and marinate for a minimum of 1 hour up to overnight. Remove the steak from the refrigerator and bring to room temperature before cooking.
Thinly slice the bell peppers and the red onion. Set aside
Heat a cast iron skillet or prepare the grill for medium-high heat. Remove steak from the bag and shake off any excess marinade. Add 1 T olive oil to the skillet or oil grill.
Cook steak over medium heat, turning once until the internal temperature of the thickest part of the steak reaches 135°.
Remove from the skillet or grill and place on a cutting board. Let rest for 5 minutes.
If cooking the steak in a cast iron skillet, add sliced peppers and onions to the hot skillet and saute until charred and tender. Season to taste with salt and pepper. If using a grill, add peppers and onions to a grill pan and grill until charred and tender.
Slice the steak on the diagonal and serve with roasted potatoes and grilled peppers and onions. Garnish with chopped parsley.