in a pot, submerge mixed mushrooms in 1 cup hot water, let sit until fully softened ~30 minutes (i use a pot because i feel like having a lid helps with rehydrating, you can also use a bowl and place a plate across the top!)

remove mushrooms from the liquid and give them a rough chop

strain remaining stock through a sieve to remove any sediment

add oats to a pot and heat up over medium heat, lightly toast your oats until they smell warm and almost sweet ~3-5 minutes

pour in your mushroom stock, water, and chopped mushrooms. bring to a boil and let simmer on low heat for ~8-10 minutes, stirring it every couple of minutes. to prevent the content from boiling over, leave the pot lid slightly ajar

season with salt to taste and serve with toppings of choice! i prefer bright toppings (like snap peas) with this since the oatmeal is pretty umami and earthy