Makes 4 burgers
It all started with the mushrooms. They were languishing in the fridge, having been accidentally left out of a soup I’d made. That they brushed against the unopened jar of Asian oyster sauce as I was pulling them out of the bin was all the inspiration I needed to tinker. One thing led to another, and presto change-o, I had made an umami-packed mushroom mix that ended up in that evening’s hamburger and many others since.
The mushrooms are sautéed with onions and then finished with a blend of oyster sauce (or Indonesian kecap manis), soy sauce, gochujang (sometimes referred to as Korean ketchup) and Asian sesame oil. The blend is sweet and hot and spicy and salty and addictively good, which kind of defines umami; worked into ground beef, it’s magical. And if you forgo the usual ketchup and slather some bulgogi sauce on your bun, you’ll have a wild, wonderful and wholly unusual burger.
Working Ahead
You can make the mushroom mix up to 4 days ahead and keep it tightly covered in the refrigerator. The burger patties will have more flavor if you make them ahead and refrigerate them for up to 1 day; you can also freeze them for up to 2 months.
Stir together the oyster sauce, soy sauce, gochujang and sesame oil in a small bowl. Taste and add more gochujang, if you’d like. Set this seasoning sauce aside.
Working in a medium skillet over medium heat, warm the canola oil. When it’s hot, add the mushrooms and onion and cook, stirring frequently, for 2 minutes, at which point the mushrooms will have released most of their liquid. Season with a bit of salt and a few grinds of pepper and cook for another 4 minutes or so, until the liquid has evaporated. Add the water and stir to pick up any bits stuck to the bottom of the pan. Remove the pan from the heat, wait 1 minute and then stir in the seasoning sauce. Scrape the mushroom mix into a bowl and let cool. (You can make this up to 4 days in advance; keep it tightly covered in the refrigerator.)
Put the beef in a bowl, add the seasoned mushrooms and mix gently to combine evenly. Taste and see if you’d like to add more salt or pepper. Shape into 4 patties. (If you’d like to give the mushroom flavor time to permeate the patties, wrap them and stow them in the fridge for up to 1 day; bring to cool room temperature before cooking.)
You can cook the burgers on a grill pan or in a heavy skillet; coat either one lightly with cooking spray. Place the pan over high heat, and when it’s hot, slip in the burgers. Cook for 4 minutes without moving them — you want to get them nicely charred. Carefully flip them over and cook for another 3 to 4 minutes for medium-rare — make a small cut in one to check the cooking; cook longer if you want the burgers more well done.
Transfer the burgers to the buns, set out whatever sauce and/or toppings you’ve chosen and serve immediately.