Other non-Chinese items that I've seen on dim sum menus include:

1) Mini veggie samosas with a Malaysian curry dip (sighted in Hong Kong)

2) Pastel de nata (sighted in Singapore, Hong Kong and Guangzhou)

3) Banh cuon - described as Vietnamese style cheung fun (Imperial China in Teddington)

4) Korean-style marinated octopus (at the defunct Laureate in London's Chinatown)

5) Japanese-style marinated octopus (Yum Cha in Camden)

6) Thai-style chicken feet (everywhere!)

I think Scotch Egg has the potential to be the cross-over dish that sees Blighty properly represented on a dim sum tick-sheet!