01 - Preheat the oven to 425°F (220°C). Line a baking sheet with parchment paper if desired.
02 - Toss the quartered mushrooms with 2 tbsp olive oil, sea salt, black pepper, and thyme directly on the baking sheet. Spread in an even single layer. Roast for 20–25 minutes, stirring once halfway through, until the mushrooms are golden brown and tender.
03 - While the mushrooms roast, heat 2 tbsp olive oil in a medium saucepan over medium heat. Add the diced onion and sauté for 3–4 minutes until translucent. Stir in the minced garlic and cook for 1 minute until fragrant.
04 - Add the rinsed brown rice to the saucepan and stir continuously for 2 minutes to toast the grains, which enhances their nutty flavor.
05 - Pour in the vegetable broth and bring to a boil. Reduce heat to low, cover with a tight-fitting lid, and simmer for 30–35 minutes until the rice is tender and all liquid has been absorbed.
06 - Remove the saucepan from heat. Fluff the rice with a fork, then fold in the lemon zest, lemon juice, chopped parsley, dill (if using), salt, and black pepper until evenly distributed.
07 - Gently fold the roasted mushrooms into the seasoned rice. Taste and adjust salt and pepper as needed. Serve warm, garnished with extra fresh herbs and a lemon wedge alongside.