Preparation Heat oil in large skillet over medium-high heat. Add onion and garlic; sauté until onion is very tender, about 8 minutes. Add beef and sauté until brown, breaking up with back of fork, about 5 minutes. Add chili powder, oregano, and sugar; stir 30 seconds. Add beans, corn, and tomato sauce. Cover; simmer until beef is cooked through, stirring occasionally, about 8 minutes. Mix in cilantro and lemon juice. Season with salt and pepper. Line 8 serving bowls with tortilla chips. Spoon beef mixture over chips. Top with cheese and sour cream.
Preparation Heat oil in large skillet over medium-high heat. Add onion and garlic; sauté until onion is very tender, about 8 minutes. Add beef and sauté until brown, breaking up with back of fork, about 5 minutes. Add chili powder, oregano, and sugar; stir 30 seconds. Add beans, corn, and tomato sauce. Cover; simmer until beef is cooked through, stirring occasionally, about 8 minutes. Mix in cilantro and lemon juice. Season with salt and pepper. Line 8 serving bowls with tortilla chips. Spoon beef mixture over chips. Top with cheese and sour cream.