Drain the canned tomatoes and chilies thoroughly to prevent the mixture from becoming watery.

In a large mixing bowl, combine the sour cream, drained tomatoes, taco seasoning, and ranch seasoning mix. Stir until completely smooth.

Fold in the shredded Mexican blend cheese until evenly distributed.

Cover the bowl tightly and refrigerate for at least 1 hour to allow the flavors to meld.

Garnish with chopped green onions if desired, and serve chilled with sturdy tortilla chips.