If you are without a food mill I would agree with the suggestion on using a colander but a sturdy stainless one. I have never tried it as I have a food mill but it sounds reasonable.

If you're going to "rice" canned tomatoes straight from the can, I'd think it would work OK, but as Michael Hoffman says, be prepared for a mess. Don't wear good clothes, and work in a HUGE bowl or pot, and I'd put it in the sink for easiest clean-up. But it should work fairly well. I don't know you'd get exactly the texture you'd get from a food mill, but I'd guess it would be close, since the ricer will catch the seeds an immersion blender or regular blender wouldn't,

I would NOT "rice" canned tomatoes that had already been cooked. I think that would be a slimy mess. And I think trying to "rice" fresh tomatoes would give you way too much waste.

The colander is another interesting option, but I'd think it would depend upon if it were the type of colander with holes or with wire mesh. That would impact the final texture of the tomatoes. May not be an issue with the dish you have in mind, but something to think about.

I just use a colander. I pour the stewed tomatoes in, and take my biggest wooden mortar to push through as much as I can, until it's mostly just skin and seeds left behind. Any kitchen that has a ricer probably also has some kind of colander, they're pretty basic pieces of equipment.

Hey, Moriah! I assume we're talking canned peeled tomatoes that have been simmer for a while, right? In that case, I think you might be able to make this work, though it'll probably make a huge mess. If you can, though, I'd borrow a food mill from a friend and do it right. Or use (or borrow) an immersion blender, which, while it won't deliver the same result, will allow you to leave some chunks in there. Alternatively, use a regular blender, but only a little.