To make the chili, combine 10 cups lobster stock, roasted green chiles, serrano, squash, onion, and oregano. Bring the stock to a boil, reduce to a simmer, and cook for 45 minutes, mashing with the potato masher until the squash and chiles begin to dissolve and the liquid reduces by a quarter. Do not puree. Add the masa harina mixture and stir to thicken. Add more masa dissolved in hot water, if needed, until the chili reaches the desired consistency. Salt to taste.