For the carmelized onion dip...do you mean Spanish onion like in red onion..

My friend Mr. Google has informed me a Spanish Onion is a large onion with mild flavor. Go with a large yellow onion and you're fine. I made this dip last year and actually planned on making it again this week, it's deeelish.

The recipe is on the Food52 iPad app for holiday recipes and party planning guide

Not sure which recipe you are referring too but generally speaking caramelized onions are not made with red onions. Any yellow onion will do.