Warm the oil in a large skillet on medium-high heat.
Add the ground beef and diced onion, breaking up the meat as it cooks until browned and no longer pink, about 7 minutes.
If needed, pour off any excess fat from the skillet.
Sprinkle in salt, pepper, chili powder, cumin, oregano, and tomato paste, stirring well to mix all seasonings evenly.
Pour in the brown rice pasta, diced tomatoes with green chiles, and chicken broth, then stir everything together.
Bring the mixture to a rolling boil, then lower heat to maintain a steady simmer and cook, stirring occasionally, until the pasta is tender but firm, about 13 minutes.
Turn off the heat; if desired, mix in the shredded cheese and let it melt for a few minutes.
Serve the pasta topped with chopped cilantro, sliced avocado, jalapenos, and radishes for added freshness and flavor.