Bring water to a boil, stir in the yellow rice, reduce heat to low, cover, and cook about 20 minutes.
When you add the rice, stir in the canned chicken and break it up. (One can works in a pinch.)
While the rice cooks, thaw corn under hot water and drain & rinse the black beans.
Once rice and chicken are done, stir in the Ro-Tel, black beans, corn, salsa, salt, and cumin. Go easy on the salt — several components are already seasoned.
Pour into a 9x13 casserole dish and spread evenly.
Top with a generous, even coating of shredded sharp cheddar.
Bake at 350°F for 20 to 30 minutes, until hot, bubbly, and melted.
Scoop onto plates, add sour cream, and ring with tortilla chips. Serve nacho-style.