Wash and dry all produce. Core, deseed, and thinly slice green pepper. Dice tomato. Zest lime until you have 1 tsp; quarter lime. Mince garlic. Finely chop cilantro. Slice corn kernels off cob; discard cob. Halve, peel, and thinly slice shallot; mince a few slices until you have 1 tsp (2 tsp for 4 servings). Mince chili, removing ribs and seeds first for less heat.

Heat a drizzle of oil in a large pan over high heat (if using a nonstick pan, heat without oil). Add corn kernels and cook, stirring occasionally, until golden brown and slightly charred in spots, 4-6 minutes. (TIP: If corn begins to pop, cover pan with a lid.) Season with salt and pepper. Turn off heat; transfer to a medium bowl.

Heat a drizzle of oil in same pan over medium-high heat. Add green pepper and cook, stirring, until slightly softened, 2-3 minutes. Add sliced shallot and cook, stirring, until lightly browned and softened, 2-3 minutes more. Season with salt and pepper. Turn off heat; transfer to a plate.

Heat another drizzle of oil in same pan over medium-high heat. Add pork and cook, breaking up meat into pieces, until browned and cooked through, 4-5 minutes. Set aside 1 tsp garlic, then add remaining garlic to pan. Season with salt and pepper and stir to combine. Stir in cooked veggies, tomato paste, stock concentrate, half the cumin, and 1/4 cup water (1/3 cup for 4 servings). Cook, stirring, until slightly thickened, 2-3 minutes. Season with salt and pepper. Turn off heat.

To bowl with corn, add cilantro, minced shallot, reserved 1 tsp garlic, remaining cumin, juice from 2 lime wedges, and 2 TBSP olive oil (3 TBSP for 4 servings). Season with salt and pepper and stir to thoroughly combine. In a small bowl, combine sour cream, lime zest, salt, and pepper. Stir in water, 1 tsp at a time, until mixture reaches a drizzling consistency.

Wrap tortillas in damp paper towels and microwave on high until warm, about 30 seconds. Fill each tortilla with pork mixture, tomato, and chimichurri. Drizzle with crema. Garnish with chili if desired. Serve with remaining lime wedges on the side for squeezing over.