Place the canned diced tomatoes and green chilies into a fine-mesh sieve and allow to drain for 5 minutes to ensure no excess liquid remains.

In a large mixing bowl, combine the sour cream and the dry ranch seasoning mix.

Stir the sour cream mixture until the seasoning is evenly distributed and no clumps remain.

Fold in the drained diced tomatoes and green chilies, shredded cheddar cheese, garlic powder, and chopped cilantro.

Stir gently until all ingredients are well combined.

Cover the bowl with plastic wrap and refrigerate for at least 2 hours to allow the flavors to meld and the texture to firm.

Serve chilled with corn chips or crackers.