While awaiting responses, I've been trying out some of the (free/trial) software I've located. Many of these have proven rather lackluster, but on first blush I'm fairly impressed by
Gourmet Recipe Manager, which is free and open source, although still in "alpha" stage. It is available for Windows and *nix (including, apparently, MacOS), although the Windows port appears to be lagging behind a bit. Its utilities for importing recipes from various web sites look quite handy; it tries to identify metadata tags (e.g. ingredients, yield, preparation time) based on the source, but allows you to modify the tagging before you import (which, in practice, is usually necessary).
It has several export options, including plain text and HTML (as well as MealMaster, which appears to be a fairly "standard"/portable recipe format). The plain text is perfectly readable, but lacks a TOC/index. The HTML is more functional, but it creates a group of files (one recipe per file, plus an index file). This can be converted into a single MOBI file via Calibre, which creates a TOC and working hyperlinks . . . but it doesn't look particularly pretty. Perhaps some tweaking will make it look nicer?
For reference, this is what the converted file looks like on the Kindle:
(And yes, that source link works with the Kindle's web browser.)
Anyway, I would still value input from others who are doing something similar!