Wash and dry all produce. Slice corn kernels off cob; discard cob. Dice tomato. Halve, peel, and mince shallot. Zest and quarter lime (quarter both limes for 4 servings). Roughly chop cilantro leaves and stems.

Heat a drizzle of oil and 1 TBSP butter (2 TBSP for 4 servings) in a large pan over medium-high heat. Add corn and cook, stirring occasionally, until tender and lightly charred, 4-6 minutes. (TIP: If corn begins to pop, cover pan.) Season with salt and pepper. Turn off heat; transfer to a medium bowl. Wipe out pan.

Meanwhile, in a small bowl, combine sour cream and lime zest. Add water, 1 tsp at a time, until mixture reaches a drizzling consistency. Season with salt and pepper.

Pat chicken dry with paper towels; season all over with salt, pepper, and Southwest Spice. Sprinkle with 1/4 tsp ancho chili powder (1/2 tsp for 4 servings; we sent more). Heat a drizzle of oil in pan used for corn over mediumhigh heat. Add chicken and cook, stirring occasionally, until browned and cooked through, 4-6 minutes.

To bowl with corn, stir in tomato, cilantro, and a few pinches of shallot (add as much or as little as you like). Taste and add lime juice, salt, and pepper. For a smoky kick, add a pinch of remaining ancho chili powder.

Wrap tortillas in damp paper towels and microwave until warm and pliable, about 30 seconds. Divide warmed tortillas between plates and fill with chicken, corn salsa, and crema. Serve with remaining lime wedges on the side.