Place 1 ½ cups refried beans in microwave-safe bowl. Place bowl in microwave and microwave beans 3 minutes, pausing to stir beans every 30 seconds, until beans are evenly hot.
Transfer beans to serving dish and spread out evenly, covering bottom of dish and leaving top of bean layer as flat as possible.
Cover dish with plastic wrap and place in refrigerator. Chill beans 10 minutes.
While beans chill, add 1 ½ cups full-fat sour cream and 2 ½ tablespoons taco seasoning to small mixing bowl. Stir ingredients together until fully combined. Set aside.
Remove serving dish from refrigerator and discard plastic wrap.
Place 2 cups guacamole on top of refried bean layer. Spread guacamole out evenly to edges of dish, covering bean layer completely.
Transfer seasoned sour cream to serving bowl. Spread sour cream out evenly to edges of dish, covering guacamole completely.
Sprinkle 1 ½ cups shredded Mexican cheese blend evenly over top of sour cream layer, covering sour cream completely.
Top shredded cheese layer with 2 medium fresh red tomatoes (diced), then cover dish with plastic wrap.
Seal plastic wrap tightly but be careful not to mash layers together or squeeze moisture out of tomatoes. Return dish to refrigerator and chill 30 minutes or until ready to serve.
To serve, remove dish from refrigerator and discard plastic wrap. Serve dip chilled with tortilla chips or vessels of choice.