In a skillet over medium heat, add the ground Mexican chorizo (if using) and cook until browned, breaking it up with a spatula. This should take about 5-7 minutes. Once cooked, transfer it to a mixing bowl and set aside.
In the same skillet, add the chopped yellow onion and poblano pepper. Sauté until the onion is translucent and the poblano is tender, about 5 minutes. Add the grated garlic and cook for an additional minute until fragrant.
In the mixing bowl with the chorizo, add the sautéed vegetables, shredded cheddar cheese, cubed Monterey Jack cheese, shredded mozzarella, and chopped chipotle chile. Mix everything until well combined.
Take a warm corn tortilla and spoon a generous amount of the cheese mixture into the center. Roll the tortilla tightly around the filling and secure it with a toothpick if necessary. Repeat this process until all the mixture is used up.
In the skillet, heat a thin layer of oil over medium-high heat. Once hot, add the taquitos seam-side down. Fry for about 3-4 minutes on each side or until golden brown and crispy. Use tongs to flip them carefully.
Once cooked, transfer the taquitos to a plate lined with paper towels to absorb excess oil. Serve immediately with yogurt, salsa, shredded lettuce, pickled onions, and avocado on the side.