Father's Day is June 16
Ultimate Umami Grilled Cheese Sandwich

Mayonnaise. It's such a divisive condiment. People loooove it or haaaate it passionately. Working at Umami Mart, I overhear a lot of conversations between people when they see we carry Japanese Kewpie Mayonnaise in our conbini (Japanese for convenience store) food section. I've heard customers proclaim, "THIS is the BEST mayo in the world!" and others groan or say, "Ugh! Gross!" about it. Hearing the reactions inspired me to create a recipe using Kewpie mayo that almost everyone* could enjoy: a grilled cheese sandwich. But not just any grilled cheese sandwich. The Ultimate Umami Grilled Cheese.

Kewpie is beloved by many, including chefs like David Chang, who are starting to incorporate it into their cuisine, making inventive recipes beyond dressings and burgers. It's ultra smooth and creamy, with a slightly sweet, slightly tangy, but mostly savory flavor. Kewpie's different than American mayo in that it's made with egg yolks and rice and apple vinegars, but the big reason it tastes so good is largely this: the notorious MSG. Monosodium glutamate ups the savory flavor, big time.

It seems like most people who hate mayo are grossed out by its look and texture, so I decided to use Kewpie in a more stealth way for this grilled cheese recipe. In fact, if you didn't see the ingredient list before tasting this sandwich, you might never know you were eating mayo. While not visible, it still adds a lot of flavor, which I proved after making two grilled cheese sandwiches – one with Kewpie and one without. The Kewpie-enhanced grilled cheese won, hands down. In addition to Kewpie, I chose several other major umami-enhanced ingredients to include in this sandwich, including Umami Salt (a blend of sea salt, dried shiitake mushrooms, and black garlic powder, handmixed for Umami Mart by Oaktown Spice Shop), fresh mushrooms, four types of cheeses (a blend I chose for their sharpness, nuttiness, and melty gooeyness), and butter, which is an umami flavor carrier.

* Excluding vegans, people who allergic to cheese, gluten-intolerant people, etc. You know who you are.

The Ultimate Grilled Cheese Sandwich
Serves 1-2, depending on hunger (and size of bread slices)


2 slices from a crusty loaf. I chose Acme Pain au Levain and cut 1-inch slices from the largest diameter of the loaf
1/4 cup shredded sharp, aged cheddar cheese
1/4 cup shredded aged Gruyere cheese
1/4 cup shredded Fontina
5 button mushrooms, sliced
2 tbsp butter, separated equally and at room temperature
Approx. 1 tbsp Kewpie mayo
1 tbsp grated Parmesan cheese
Umami Salt, to taste


1. Using 1 tbsp of the butter, divide in half. Spread 1/2 tbsp of butter evenly on each slice of bread. Make sure you're spreading on what will be the interior of your sandwich.

2. Flip the bread slices over and slather a thin coating of Kewpie mayo on what will be the exterior of your sandwich. I just squeezed directly from the bottle and used a butter knife to evenly coat the bread.

3. Apply a light, even layer of parmesan cheese onto the newly Kewpied bread slices. Secure the grated cheese onto the mayo glue by gently pressing with your fingers.

4. Heat a pan on medium-high and melt the remaining 1 tbsp of butter. When butter is melted and slightly foamy, add sliced mushrooms. Stir to coat each slice.

This might seem obvious, but prepare all your ingredients before you start cooking and have them close at hand. You don't want to be working with cold mushrooms or be shredding cheese while the bread is already on the stove, or else you'll end up with a half-melted sandwich or burnt bread!

5. Add Umami Salt – about 1/4 tsp or more to taste – to the mushrooms and continue to saute until shrooms release their juices, reduce in size, and become slightly browned. This will take about 5 minutes. Remove the cooked mushrooms from the pan and set aside in a small ramekin. You'll want these to remain as warm as possible and close at hand.

6. Using the same pan and keeping the heat at medium-high, place the bread slices, butter side down into the pan and cook for 2 minutes, until slightly toasted.

7. Flip onto parm-crusted Kewpie side. While the buttered side is still hot, place shredded cheese and still-warm mushrooms onto bread.

8. Close sandwich and press. I used a Bacon Press, but you can use a spatula or a smaller, heavy pan for the same effect. Cook for about 1 minute and flip. Press again and cook for another minute, until both sides are crusty and brown, but not burnt.

The bread should have a golden brown parmesan crust.

9. Remove from pan, cut in half, and enjoy immediately. As this sandwich is pretty rich, buttery, and cheesy, I suggest eating with some pickles, like cornichons and pickled red onions.

Conbini Creations is an experiment in cooking with ingredients found in the conbini, or convenience store section, of Umami Mart's Oakland retail shop.