avocado relish

2 ripe California avocados
1 small vine-ripened tomato
2/3 cup finely chopped white onion (about 1/2 onion)
1 to 2 fresh serrano chilies
2 tablespoons chopped fresh coriander sprigs
2 teaspoons fresh lime juice
1 teaspoon coarse salt
1/2 teaspoon coarsely crushed black peppercorns