I am willing to forgo a little taste if I don't have to take 3 breaks while dicing an onion. Should I use red, white or yellow to minimize eye irritation. I have a small fridge/freezer so freezing them isn't an option.
The onions that cause the least tears are those with lower sulfur content. But it turns out that it's not just the variety of the onion that's a factor, but the sulfur content of the soil they're grown in (eg, areas of Georgia, where Vidalia onions are grown). Of course, this means they don't have the same 'bite' as you'd get from other onions.
In the U.S., at least, they're typically sold as 'Sweet' onions. They may go under names such as Vidalia, Maiu Sweet, Mayan Sweet, Walla Walla, etc. They tend to be yellow varieties, but they're fairly obvious in their shape-- they're not round, they tend to wider than the length from the ends. They also tend to be more wet than regular onions, so they don't store as well, and thus have a shorter season (or they're flown in from South America, for those of us in the U.S.)
If I were to rank them, from least to most tear-causing, I'd say:
- sweet onions
- green onions / scallions
- red onions
- other yellow onions
- white onions
I think that sweet onions cause the least crying, at least in my experience. Also, green onions or scallions have never made me cry. I know that onion cells, when broken give off sulfur compounds which rapidly change into other chemicals on contact with air which then become vapors that irritate the eye. Have heard of a number of ways to reduce the crying effect.
I have tried different crying reducing techniques, used refrigerated onions occasionally, have never done any 'science' on this topic. I do know, however, that sweet onions don't make me cry.
http://en.wikipedia.org/wiki/Onion gives some information about the chemical reactions.
Hope this helps