Sep 11 2026
Restaurantsunderstory oaklandKing Oyster Agua Chile Recipe

King Oyster Agua Chile Recipe

Inspired by understory oakland
Time35m
Serves4

King oyster mushrooms, coconut milk, lemongrass, ginger, cilantro, red onion, corn tostadas

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Ingredients

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Marinated King Oyster Mushrooms

Method

Marinated King Oyster Mushrooms

  1. 1

    Prepare and Sear Mushrooms

    Trim the ends of the king oyster mushrooms and slice them lengthwise into 1/4-inch thick planks or 1/2-inch long batons to resemble scallops. Pat dry. In a large skillet over medium-high heat, warm 2 tbs oil until shimmering. Season mushroom slices with 1 tsp kosher salt and 1 tsp black pepper. Sear the mushrooms in a single layer for 2–3 minutes per side until well browned and caramelized. Work in batches if needed. Remove to a plate and set aside.

Agua Chile Broth (coconut-lemongrass)

  1. 2

    Infuse Broth

    In a small saucepan combine 1 cup coconut milk, 1 cup hot vegetable stock (or water), chopped lemongrass, and sliced ginger. Bring to a gentle simmer over medium heat, then reduce heat and let simmer 6–8 minutes to infuse flavors. Do not boil vigorously.

  2. 3

    Strain and Finish Broth

    Remove from heat and strain the infusion into a bowl, pressing on solids to extract flavor. Stir in 4 tbs fresh lime juice, 1 tsp sea salt, 1 tsp agave (if using), and 1/2 tsp freshly cracked black pepper. Taste and adjust acidity or salt — the broth should be bright, slightly creamy from coconut milk, and balanced. Let cool to warm or room temperature for 10–15 minutes.

Aromatics & Veggies

  1. 4

    Quick Pickle Red Onion

    While the broth infuses, place 1/2 cup thinly sliced red onion in a small bowl. Sprinkle with 1/4 tsp sea salt and squeeze 1 tbs of the prepared lime juice from the broth mixture over the onion (or use extra lime if needed). Toss and let sit 8–10 minutes to soften and lightly pickle. If using jalapeño/serrano, add thin slices to the onion to pickle slightly as well.

  2. 5

    Prep Cilantro and Radish

    Roughly chop 1/2 cup cilantro leaves and thinly slice up to 4 radishes. Keep aside for assembly.

Garnish & Assembly

  1. 6

    Assemble Tostadas

    Place 8 corn tostadas on a serving platter. Spoon 2–3 tbs of the cooled coconut-lemongrass agua chile broth onto each tostada so it wets the surface but does not make it soggy.

  2. 7

    Top with Mushrooms and Aromatics

    Arrange 2–3 seared king oyster mushroom slices on each tostada over the moistened area. Top with a few pickled red onion slices, a couple of jalapeño slices if using, and a sprinkle of chopped cilantro. Add a thin radish slice or two for crunch and color.

  3. 8

    Finish and Serve

    Garnish with micro cilantro or extra cilantro leaves and serve immediately with lime wedges on the side for extra brightness. If you prefer a wetter presentation, serve the remaining broth in a small pitcher to spoon over at the table.

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