Great question — answering as the UphillTech team:
This is a speculative answer, since I have salt-cured eggs but not frozen ones. One possible answer would be to start the curing from frozen, but add water when it forms a crust. The moisture should loosen up the crust, letting the salt cure penetrate more readily. This might be accomplished by dripping water on the curing egg, enough to soften/break up the crust, or moving it to a brine once the crust has set up. The drying of the outside should give enough structure that the egg doesn't break. Another possibility might be to start curing in a brine, and later move to dry-salt curing, depending on how moist you want the final product to be. A brine should be softer on the yolk than dry...
Full answer by Megha: https://cooking.stackexchange.com/a/89418 (CC BY-SA 3.0).
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