Once you soak the skewers and make the coconut-peanut sauce, the rest of this recipe is a breeze.

Ingredients

• 3/4 cup kecap manis or oyster sauce
• 1 large shallot, thinly sliced (about 1/3 cup)
• 2 large garlic cloves, finely chopped
• 1 tablespoon finely chopped fresh lemongrass (from 2 stalks)
• 2 teaspoons ground coriander
• 2 teaspoons grated peeled fresh ginger
• 1 teaspoon kosher salt
• 1 teaspoon fish sauce
• 1 teaspoon vegetable oil
• 1/2 teaspoon ground nutmeg
• 1/4 teaspoon ground white pepper
• 1 pound skirt steak, flank steak, or bavette steak, cut into 1-inch pieces
• 3/4 teaspoon ground cumin
• 1 pound mixed fresh baby portobello and baby shiitake mushrooms, stemmed (about 5 1/2 cups)
• 2 tablespoons water
• 2 tablespoons lime juice
• 1/2 cup well-stirred unsweetened coconut milk
• 1/4 cup creamy peanut butter
• 2 tablespoons fresh lime juice
• 2 teaspoons coconut sugar, jaggery, demerara sugar, or honey
• 2 teaspoons soy sauce, plus more to taste
• 2 teaspoons sriracha or chile oil
• 2 teaspoons finely chopped fresh cilantro
• 1 garlic clove, finely chopped
• crushed peanuts and chopped fresh cilantro leaves, for garnish

Directions

1. Process kecap manis, shallot, garlic, lemongrass, coriander, ginger, salt, fish sauce, oil, nutmeg, and white pepper in a food processor until mostly smooth, about 1 minute. Reserve 1/4 cup kecap manis mixture in a small bowl; evenly divide remaining mixture between 2 large ziplock plastic bags. Add steak and cumin to 1 ziplock bag; massage to combine and coat. Add mushrooms and 2 tablespoons water to second ziplock bag; massage to combine and coat. Marinate mushrooms and steak in refrigerator for 30 minutes or up to 2 hours.
2. Meanwhile, whisk lime juice into reserved kecap manis mixture; set mixture aside at room temperature for up to 2 hours. Submerge skewers in water; let soak 30 minutes or up to 2 hours.
3. Process all coconut-peanut sauce ingredients in a food processor until smooth, 1 to 2 minutes. Season with additional soy sauce to taste, if desired. Transfer sauce to a medium bowl; cover and refrigerate until ready to serve.
4. Preheat grill to medium-high (400°F to 450°F). Thread 7 to 8 mushrooms onto each of 4 or 5 skewers, leaving no gaps between mushrooms. Thread 4 to 5 steak cubes each onto each of the remaining 4 or 5 skewers, leaving no space between pieces of meat. Discard marinade.
5. Brush one side of each skewer with some of the reserved kecap manis mixture; place skewers, basted side down, on oiled grates. Baste top sides of skewers with kecap manis mixture; grill, uncovered, turning and basting occasionally, until steak and mushrooms are charred and caramelized, 6 to 10 minutes. Transfer skewers to a serving platter. Drizzle skewers with coconut-peanut sauce. Garnish with crushed peanuts and chopped cilantro. Serve immediately with additional coconut-peanut sauce on the side.