Soft Tacos With Fish and Spinach

Name: Soft Tacos With Fish and Spinach
Ingredients: 1 tablespoon extra virgin olive oil; 3/4 pound fresh tomatillos, husked, or 1 13-ounce can, drained; 1 to 3 jalapeño or serrano chiles, roughly chopped; 1 thick slice of onion, roughly chopped; 2 garlic cloves, roughly chopped; Salt to taste; 24 sprigs cilantro, plus chopped cilantro for garnish; 1 tablespoon extra virgin olive oil or canola oil; 1 1/2 cups vegetable or chicken stock; 12 corn tortillas; 1 1/4 pounds cod or snapper fillets; 1 12-ounce bag baby spinach; 2 ounces mexican queso fresco or feta for sprinkling (optional)