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Cathy Katin-Grazzini

Cathy's Kitchen Prescription LLC



Corny Crostini with Mushrooms


If you have corn grits on hand you can make very tasty crostini. Personally, I like to use the coarsest grits I can find for their flavor and texture, so I made these with deliciously rustic xerém grits, popular throughout the Portuguese colonial diaspora from Brazil to Cape Verdes Islands. But instant polenta works too.  Toasted briefly on the grill and topped with a delicious mushroom sauté and you’ve got a crowd-pleasing appetizer or a light supper. The crostini have a crispy exterior and a soft interior. The woodsy mushroom umami flavors create a worthy complement. Xerém corn is nixtamalized, unlike polenta by the way, making the corn’s niacin bioavailable.  Every element of this dish is fiber-rich, low in fat, and generates very few carbon emissions.


Note: Xerém grits are found at any Latino grocery or online. If using instant polenta, choose one with a coarser grit like Bob’s Red Mills.


Prep time 45 minutes to prep ingredients plus 1 hour for the cooked corn to solidify

Cook time 30 minutes

Makes about 12 crostini, depending on size


1 cup xerém hominy grits or instant polenta

About 5 cups water

3 cups fresh mushrooms, mixed varieties

1 teaspoon porcini powder from 2 teaspoons dried porcini mushrooms

¾ teaspoon granulated onion

¾ teaspoon granulated garlic

½ teaspoon dried thyme leaves

Up to 2 tablespoons arrowroot

1/3 cup aka (red) miso paste, or to taste

Coarse grinds of black pepper

Fresh herb leaves for garnish


Both xerém and polenta need to cool and solidify before being cut into crostini, so cook it in advance.


In a medium pot bring 3 cups of water to a boil. Dissolve 2 to 3 tablespoons of aka miso in the water, tasting it to ensure it is mildly flavored but not overly saline.  Pour in the corn, stirring constantly.  Xerém is not precooked like instant polenta, so it will need to rehydrate before cooking. Allow it to boil for two minutes, then turn off the heat and cover. Wait about 30 minutes for the corn to soften before proceeding.  


When the corn has softened, bring it to a simmer and cook for about 15 minutes, stirring frequently to prevent sticking to the pot.  Instant polenta does not require soaking and will cook in about 6 to 8 minutes.


When the corn grits are tender and the texture has become dense, pour it onto a large wooden board. With an offset spatula spread it into a rectangle one-half inch thick to cool most quickly.  Use the spatula to square the corn’s edges as best you can.  Set it aside for an hour to cool and solidify as you prep and cook the mushrooms.


Grind the dried porcini in a coffee or spice grinder, creating a uniform powder. 


Cut off any roots on the mushrooms and brush off any grit.  Use your hands to pull the stems apart. Place them in a large skillet. Add the dried thyme, stir in two tablespoons of the red miso, and grinds of black pepper.  Cover the mushrooms with water, about 2 cups. Cover the pan and bring to a simmer. Cook for 15 minutes and test for doneness. Only when the mushrooms are uniformly tender, remove them with a slotted spoon to a bowl. When they are cool enough to handle, transfer them to a food processor. Pulse once or twice to cut them into small, similarly sized pieces but do not overprocess.


You should have about a cup or slightly more of the mushroom water in the pan. Use a small whisk to mix in a tablespoon of arrowroot. Bring to a simmer and cook until the liquid has thickened into a smooth sauce, thin enough to slowly drip off a spoon. If it is too watery, add more arrowroot. If it is too dense, add a little water.  When the sauce is ready, stir in the chopped mushrooms. Season to taste with the porcini powder, granulated onion and garlic. Correct any seasonings, as you like. Cover to keep warm and turn off the heat.


Now fire up the grill on medium. Alternatively, you can heat a good quality nonstick pan to toast the crostini.


Cut the solidified xerém or polenta into rectangles about 1½ by 3 inches. The crostini will shrink slightly as they cook on the grill or in the pan. Grill/toast for a few minutes on each side, until you see light grill marks or darkening on the toasted edges. Flip and repeat. 


Serve the crostini while they are warm. Spoon the mushroom mix on each crostino and top with a few fresh aromatic herb leaves.  If you make these crostini in advance, reheat them for 30 seconds in the microwave before serving.

Corny Crostini with Mushrooms

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