For the Pico de Gallo, combine all tomatoes, cilantro, red onion, jalapeño peppers, lime juice, olive oil and salt. Cover and refrigerate until ready to use. Use any fresh, juicy tomatoes and adjust proportions to your own taste. Makes about 2 cups.
Preheat oven to 325°F.
Toss pork with garlic, jalapeños, cumin, salt and pepper. In a large saucepan, heat olive oil over medium-high heat. Add pork and cook, stirring frequently, until lightly browned on all sides, about 10 minutes.
Transfer to roasting pan and add orange juice, lime juice and chicken stock. Cover tightly (you don't want to lose the steam from a loose fitting lid) and place in oven for 2 to 2 1/2 hours, until meat is very tender. If juices cook out, add more chicken stock.
Allow pork to cool and absorb remaining juices. Shred meat with a fork.
To serve, pass warmed tortillas and allow each person to make their own tacos.