After figuring out the "secret" of curry from the home style recipe I found, I tried again with turkey leftovers.
The secret is 1) toasting spices in a bit of oil (cumin, peppercorns, etc.) and 2) pureeing an onion or two and sauteing it in the toasted spice oil until the onions brown a bit.
The pureed onions add a solid backbone to the sauce, both in terms of flavour (sweet + caramelized) and texture (no flour or other thickening agents needed).
This was served with roti that Rachael made, which also turned out the best yet.