A mucilage is what things like flax and okra produce. Starch can be used to make a mucilage too. I’ve tried corn starch and tapioca starch, it takes around a tablespoon per cup of water for that consistency, or you can make it thicker, like papeda, by adding twice as much starch. It has to be stirred into the unheated water until blended (which looks like milk), then heated and stirred continuously until it thickens (gelatinizes), which is at around 170°F. The tapioca starch is better for refrigerating or freezing as a mucilage, because the cornstarch will separate from some of the water when chilled (unless it is ‘modified cornstarch’). By the way, googling “egg substitute starch” will list others that are used for this. I haven’t really used it this way, but it’s obviously similar when you see a clear thickened liquid like that.
