Step 1

Mix sour cream and lime juice in a small bowl; cover and chill.

Step 2

Heat oil in a large skillet over medium heat. Cook chorizo, breaking up meat and stirring occasionally, until browned and fat is rendered, 6–8 minutes. Using a slotted spoon, transfer chorizo to paper towels to drain (do not pour off fat from skillet).

Step 3

Add sweet potato to skillet and cook, stirring occasionally, until golden brown and tender, 8–10 minutes. Mix in chili powder and cayenne, season with black pepper, and cook, stirring, 30 seconds. Using a slotted spoon, transfer to a paper towels to drain; season with salt.

Step 4

Meanwhile, whisk eggs in a large bowl to blend; season with salt and pepper. Heat butter in a large nonstick skillet over medium heat. Cook eggs, stirring occasionally and scraping bottom of skillet with a heatproof spatula to form large curds, until just set, about 3 minutes. Remove from heat and mix in chorizo.

Step 5

Fill tortillas with egg mixture and sweet potatoes and top with lime crema, Tomatillo Salsa, Rice Vinegar–Pickled Red Onions, and cilantro.