Tomatillo Salsa

Ingredients

• 1/4 cup chopped onion
• 2 tablespoons cilantro
• 2 tablespoons shredded watercress
• 1 teaspoon vegetable oil
• 1/4 teaspoon salt
• 1/2 pound tomatilos, cut in half
• 1 or 2 green chiles, seeded