Step 1

Place monterey jack and cheddar cheese in a medium bowl and toss with cornstarch until evenly coated. Set aside.

Step 2

Heat oil in a medium saucepan over medium-high heat until shimmering. Add in onion and cook, stirring occasionally, until softened and lightly browned around the edges, about 5 minutes. Add in jalapeño, garlic, chili powder, cumin, and oregano and cook until fragrant, about 30 seconds. Add in ground beef and cook, breaking up with a wooden spoon, until browned, about 5 minutes. Stir in salsa, reduce heat to medium, and simmer for 5 minutes.

Step 3

Stir in evaporated milk, scraping bottom of pan to release any fond, and bring to a boil. Reduce heat to low and add in cheese. Stir constantly until cheese is melted and smooth. Stir in sour cream, cilantro, and lime zest. Season with salt to taste. Transfer to a bowl and serve immediately.