To prepare the pesto: In a food processor, combine mint, parsley, almonds, Parmesan cheese, the water, lemon juice, garlic, 1/8 teaspoon of the salt, and 1/8 teaspoon of the pepper. Cover and process until nearly smooth. Set aside.
Rinse scallops and pat dry with paper towels. Sprinkle scallops with the remaining 1/8 teaspoon salt and 1/8 teaspoon pepper. In a large nonstick skillet, heat oil over medium-high heat. Add scallops; cook for 4 to 5 minutes or until scallops are opaque, turning once halfway through cooking.
Serve scallops and pesto over watercress.
3 lean meat, 1 1/2 fat, 1/4 vegetable