Preheat the oven to 350°F (175°C).
In a large bowl, combine 1 cup sour cream, 8 ounces softened cream cheese, and 2 tablespoons taco seasoning until smooth and well blended.
Spread the refried beans in an even layer in an 8x8-inch baking pan or 2‑quart casserole dish.
Dollop the seasoned cream cheese mixture over the beans, then gently spread it into an even layer to fully cover the beans.
Sprinkle 1 cup shredded cheddar cheese evenly over the top of the dip.
Bake for 20–25 minutes, until the cheese is melted and the dip is heated through.
While the dip bakes, combine halved grape tomatoes, minced yellow onion, and chopped cilantro in a small bowl; season with a pinch of salt if desired.
Remove the dip from the oven and top with the tomato mixture. Serve immediately with tortilla chips.