Brown meat over medium-high heat in large skillet, stirring to crumble. Add onion and garlic; cook until soft but not brown. Drain fat. Add salt, cumin, pepper and rice. Remove from heat; cool.
Combine lettuce, tomatoes, cheese, avocado, and rice mixture in large bowl. Add sour cream and toss lightly. Serve immediately with picante sauce and corn chips, if desired.