Frankly, unless you're drying peas you harvested and shelled, you might want to consider just looking for dried, whole peas in the Hispanic section of the grocery store. Goya makes a good, dried, whole pea. It just saves time and money compared to drying frozen peas.
Roger's Rangers would make a thick, pea soup, and freeze it, then hack a chunk off of the block and add it to boiling water, but that's not "portable soup", which is a sort of boullion type concoction...,
PORTABLE SOUP
INGREDIENTS.—2 knuckles of veal, 3 shins of beef, 1 large faggot of herbs, 2 bay-leaves, 2 heads of celery, 3 onions, 3 carrots, 2 blades of mace, 6 cloves, a teaspoonful of salt, sufficient water to cover all the ingredients.
Take the marrow from the bones; put all the ingredients in a stock-pot, and simmer slowly for 12 hours, or more, if the meat be not done to rags; strain it off, and put it in a very cool place; take off all the fat, reduce the liquor in a shallow pan, by setting it over a sharp fire, but be particular that it does not burn; boil it fast and uncovered for 8 hours, and keep it stirred. Put it into a deep dish, and set it by for a day. Have ready a stewpan of boiling water, place the dish in it, and keep it boiling; stir occasionally, and when the soup is thick and ropy, it is done. Form it into little cakes by pouring a small quantity on to the bottom of cups or basins; when cold, turn them out on a flannel to dry. Keep them from the air in tin canisters.
Average cost of this quantity, 16s.
Note.—Soup can be made in 5 minutes with this, by dissolving a small piece, about the size of a walnut, in a pint of warm water, and simmering for 2 minutes.
LD