Step 1

Heat oil in a pot over medium-high. When it shimmers, add mushrooms and onion; season with salt and pepper. Cook, stirring occasionally, until tender and golden brown in places, 10 to 12 minutes. Add grains and cook, stirring a few times, until toasted and nutty, 2 to 3 minutes.

Step 2

Add broth; bring to a boil, then reduce heat to medium-low and simmer until grains are just cooked, 12 to 15 minutes. Remove from heat. Stir in Pecorino and lemon juice; season with salt and pepper. Serve with watercress, a drizzle of oil, more cheese, and lemon wedges.