Shrimp Tacos with Cilantro Pesto

Source: What's Cooking San Antonio? by Pat Mozersky

Cilantro Pesto
2 cloves garlic
1 to 2 serrano chiles, stemmed
2 cups cilantro
2 tablespoons pumpkin seeds (or pine nuts) toasted
    in a 350 degree F oven for 5 to 7 minutes
2 tablespoons grated Parmesan cheese
4 ounces mild goat cheese
2 to 3 tablespoons olive oil

Shrimp
2 pounds medium-size shrimp
1/4 cup olive oil
Lime juice
Red pepper flakes, optional
Salt and pepper, to taste

For serving
Flour or corn tortillas
2 to 3 avocados, sliced, optional
Salsa

To make cilantro pesto, pur