My friend Ako taught me this trick: Just slice off the tops of some tomatoes, stick 'em in a microwave-safe bowl, blast 'em for a few minutes till soft, wait for them to cool a bit, then they will peel easily. At the time, Ako was feeding her one-year-old, so she left the tomatoes pretty chunky, but Joel is still eating pureed foods, so that's what I do for him.
After you peel them, you can mush them up a bit with a spoon, and either leave them as is, or puree in a food processor or with an immersion blender (I don't de-seed).
Then freeze what you don't need at the moment, and you're good to go! Joel had some tomatoes last night with some couscous (I cooked it with chicken bouillon and olive oil) and some peas and carrots, all mashed together, and he seemed to enjoy it!