In a medium skillet, warm the canola oil over medium heat until it begins to shimmer, about 2 minutes.
Add the chorizo and cook, stirring occasionally, until it’s fully cooked and crumbly, about 10 minutes. Remove the chorizo from the pan and set aside.
Add ¼ cup of the onion and the garlic to the pan and cook, stirring occasionally, until they are soft and translucent, about 4 minutes.
Return the chorizo to the pan and cook for 3 more minutes, stirring occasionally. Remove the pan from the heat and set aside.
In a large heavy saucepan, combine the half-and-half and Velveeta and cook over medium heat, stirring occasionally, until the Velveeta is melted, 6 to 8 minutes.
Add the Mexican cheese blend and stir until the cheese has melted and the mixture is smooth, about 3 minutes.
Mix in the Hatch chiles, chipotle pepper, oregano and chili powder.
Transfer the melted queso to a warm dish or cast-iron pan and top with the reserved chorizo-onion mixture, remaining 2 tablespoons diced onion and the cilantro.
Serve immediately with tortilla chips or warm corn tortillas.
