Dim sims aren't like dim sum GB (more's the pity). You get them at truck stops, fish and chip shops and the like. Similar premise but come down several degrees!! LOL Here you say "Dim Sims" and "Chiko Rolls" in the same breath and while they aren't scorned anymore, they were in the 70's as the culturally lacking in taste brigade food!!! But like I said, they are much more acceptable now, although I don't think they have changed in any health areas. Pastry on a dim sim is quite solid from memory.
Cath, next time you are in Coles or Woolies, have a look in the frozen snack foods section. Ho Mai produce Chicken and Mushroom Dumplings and Pork and Chive Dumplings. These can be boiled or steamed and then cooked in a pan (potstickers). They will be the closest you find in the supermarkets to pirogies, just smaller and with Asian flavours.
Filling of a samosa is wrong comparison and the pastry on a pasty too thick but they are all of a similar basis, just with cultural variations.
Have a look at this site: Nowinski's Pirogies for Restaurants, Grocers, & Home Delivery in the Western New York & Buffalo Area