Cook the macaroni in a pot of salted boiling water until just al dente, about 7–8 minutes; then drain and set aside.

Heat a large skillet over medium-high heat and add the chopped onion; cook until soft and glossy, about 4 minutes.

Add the ground beef and brown, breaking it up with a spatula until no pink remains and the edges turn golden, about 6–7 minutes; drain excess fat if needed.

Stir in the diced tomatoes (with juices), tomato sauce, green chiles, corn, cumin, salt, and pepper. Bring to a simmer.

Simmer uncovered for 8–10 minutes, stirring occasionally, until the sauce thickens and coats the back of a spoon.

Fold the cooked macaroni into the skillet, heat through for 1–2 minutes, and finish with chopped cilantro. Taste and adjust seasoning.