Preheat oven to 425°F (218°C).
Heat the olive oil in a large skillet over high heat until shimmering.
Add the ground meat and chopped onion and cook, breaking the meat up, until the meat is browned, about 5 minutes.
Stir in the chipotle chili powder, smoked paprika, cumin, garlic powder, crushed red pepper, dried oregano, and 1 teaspoon kosher salt.
Add 3/4 cup water, reduce heat to medium, and simmer until the liquid thickens slightly and coats the meat, about 10 minutes.
Remove the skillet from heat and stir in 1/4 cup chopped fresh cilantro.
Arrange the hard taco shells on a sheet pan or in a 9×13-inch baking dish and warm in the oven for 5 minutes.
Divide the cooked meat evenly among the taco shells, sprinkle each with the shredded Mexican cheese, and return to the oven for about 10 minutes until the cheese melts.
Meanwhile, make the cilantro-lime ranch: combine sour cream (or Greek yogurt), 3/4 cup finely chopped cilantro, 1 teaspoon garlic powder, 1 teaspoon onion powder, chopped pickled jalapeños with 2 tablespoons pickle brine, juice from 2 limes, and 1 teaspoon kosher salt in a jar or bowl; stir or shake until smooth.
Serve the tacos topped with the cilantro-lime ranch and any additional desired toppings such as avocado or red onion.