Burgers with Spicy Dill Salsa

Ingredients

• 1 jar (10 ounces) dill pickle relish
• 3 plum tomatoes, seeded and finely chopped
• 1 small white onion, finely chopped
• 1/2 cup finely chopped red onion
• 1/2 cup minced fresh cilantro
• 1 tablespoon olive oil
• 1 to 2 serrano peppers, seeded and chopped
• BURGERS:
• 3 pounds ground beef
• 2 teaspoons salt
• 1 teaspoon pepper
• 12 hamburger buns, split