Ranchero Steak with Potatoes

Name: Ranchero Steak with Potatoes
Ingredients: 1 cup vegetable oil; 2 medium russet potatoes or 3 smaller potatoes (thinly sliced); 1 lb breakfast steak or any other thin steak (thinly sliced); 1 garlic clove (chopped); 1/2 medium white or yellow onion (thinly sliced); 1 Anaheim (jalapeño, or serrano pepper (remove seeds for less spiciness)); 3 Roma tomatoes; 4 oz tomato sauce; 1/2 tsp kosher salt (or more to taste); 1/4 tsp ground black pepper (or more to taste); 1 cup water (or more if needed while cooking)