Start by heating the olive oil in your saucepan over medium heat. Once shimmering, add the diced onion and sauté until translucent and fragrant, about 3-4 minutes. Stir in the minced garlic and cook for another minute, making sure not to let it burn.
Add the sliced mushrooms to the pan. Cook, stirring occasionally, until they release their moisture and start to brown—approximately 6-8 minutes. This step deepens the flavor and gives the pilaf a wonderful, meaty texture.
Once the mushrooms have browned, stir in the pearl couscous and the dried thyme. Toast the couscous for 2-3 minutes, stirring frequently. This enhances the nutty flavor and prevents the grains from becoming mushy.
Pour in the vegetable broth, season with salt and pepper, and bring the mixture to a boil. Once boiling, reduce the heat to low, cover the pot, and let it simmer for 10-12 minutes, or until the couscous has absorbed the liquid and is tender.
Remove the pan from heat and let it sit, covered, for 5 minutes. Then, fluff the couscous gently with a fork. Sprinkle fresh thyme leaves over the top for a burst of herbal aroma and a lovely visual touch before serving.