Placed dried California chilies in deep bowl and cover with the boiling water. Submerge chilies with a heavy bowl or cup. Let sit submerged for 15 minutes to fully rehydrate.

In a thick-bottomed stockpot, starting with 1 tablespoon oil, brown pork in batches until all pork is lightly browned, about 3 to 5 minutes per batch. Remove each batch from stockpot and place in a bowl. Be sure not to cook the meat. Set aside. If using ground pork instead, cook the ground pork all the way through, approximately 8 to 10 minutes, then set aside.

Strain the chiles, being sure to capture and reserve ½ cup soaking liquid. Place rehydrated chilies in a food processor with the reserved liquid. Pulse on high to make a thick paste. Set aside.

Add onions, garlic, coriander, salt, pepper, oregano, and red pepper flakes to stockpot with pork drippings. On medium heat, mix and cook until onions are translucent, about 5 to 8 minutes. Add the browned pork, tomatoes, squash, stock, and 2 cups water. Bring to a boil. Boil for 5 minutes, then add chile purée and mix well. Reduce the heat and simmer for 5 additional minutes.

Ladle the hot stew into hot jars, leaving 1 inch of headspace. Remove any air bubbles and add additional stew if necessary to maintain the 1 inch of headspace.

Wipe the rim of each jar with a warm washcloth dipped in distilled white vinegar. Place a lid and ring on each jar and hand tighten.

Place the sealed jars in the pressure canner, lock the pressure canner lid, and bring to a boil on high heat. Let the canner vent for 10 minutes. Close the vent and continue heating to achieve 11 PSI for a dial gauge and 10 PSI for a weighted gauge. Process quart jars for 90 minutes and pint jars for 75 minutes.