Boil a large pot of water. Salt the water and then add the pasta. Cook according to package directions until al dente. Drain, saving at least 1/4 cup of the pasta water. Return pasta to the pot.
In a large skillet over medium heat, heat olive oil. Add onion and season with salt. Cook until tender, 5 minutes.
Add jalapeño. Cook 2 minutes more.
Add ground beef and cook until no longer pink, 6 minutes. Add taco seasoning. Drain fat.
Add canned tomatoes and 1/4 cup reserved pasta water. Stir.
Add cheese. Let it melt in while stirring occasionally for about 2 minutes.
Add cooked pasta and toss until completely combined.
Garnish with cilantro and serve.