In a large nonstick pan or on a griddle, heat the oil. Add jalapeño, onions and bell peppers; sauté 2 to 3 minutes, until vegetables are soft.
Stir in steak strips and cook, stirring occasionally, until steak is seared, but not overcooked. Season with salt and pepper, to taste. Remove to a bowl and wipe the skillet.
In a large bowl, beat the eggs with a fork until well blended, then add the grated butter, mixing until well combined. The butter will emulsify into the eggs and keep them fluffy and tender, even when cooked through.
Heat the cleaned skillet over medium-low heat. Spray with nonstick spray. Pour the egg and butter mixture into the pan. Using a heat-proof rubber spatula to scramble the egg mixture until firm throughout with no visible egg liquid remaining, and large curds have formed. Season to taste with salt and pepper.
Stir in cheese until fully melted.
Gently stir eggs into vegetable mixture. Keep warm.
For each serving, heat a tortilla in a hot pan or on a griddle. Top with about 2/3 cup egg mixture and a teaspoon of sour cream. Repeat for remaining tortillas. Serve immediately with salsa, chopped cilantro leaves and lime wedges on the side.
Note: Do not let uncooked egg mixture remain at room temperature for longer than one hour (including preparation and service time).