Is it possible to make a marshmallow that isn't sweet?
What about using mochi, an Asian pounded rice paste? It's a similar—though not identical—texture, it's available in sweet and savory forms, and it's held together by the starch in rice rather than anything gelatin, so it's vegetarian. You can get plain unflavored mochi at many Asian food stores; it may take some looking, as it's more often sold sweet and filled with bean paste in the US. I've had it in savory Korean dishes and I believe it's used in savory Korean dishes as well.