1. Fill a large bowl with ice and water, and set aside. Bring a medium saucepot of water to a boil over high heat. Add 2 teaspoons salt and the favas; cook until bright green, about 3 minutes. Transfer to ice bath to cool. Squeeze favas from skins; discard skins.

2. Combine favas, 2 tablespoons olive oil, lemon juice, salt, and pepper in a medium bowl, and mash with a fork to combine.

3. Slice baguette lengthwise, and spread one side with fava mixture.

4. Layer with the avocado, pecorino, and mache; drizzle with remaining teaspoon olive oil, and season with salt and pepper. Top with remaining bread. Slice into three six-inch sandwiches.