1. Whisk together the vegetable stock, soy sauce, garlic, fennel seeds, vinegar, honey, peanut butter, red pepper flakes and cornstarch in a bowl until thoroughly combined then set aside.

2. Heat a wok or large nonstick pan over medium heat. When the pan is hot toast the cashews, stirring often, until lightly browned and fragrant, about 2 minutes. Transfer toasted cashews to a plate and set aside.

3. Add the oil to the now empty wok and tilt the pan to coat evenly. Increase the heat to medium-high and when the oil is hot add the brussels sprouts in a single layer. Let the brussels sprouts cook without moving them until charred on one side, 4 to 5 minutes. Stir the brussels sprouts and cook for about 3 more minutes, stirring occasionally.

4. Pour the sauce into the pan with the brussels sprouts and stir to combine. Cook, stirring occasionally, until sauce thickens a bit, about 2 minutes. Take the pan off the heat and stir in the sesame oil, toasted cashews, and green onion. Serve over steamed rice.