Spicy Mexican Shredded Pork Tostadas (Tinga)
From http://www.americastestkitchen.com/, Season 11: Tostadas and Empanadas

Why this recipe works: True Mexican shredded pork, or tinga, is a far cry from the bland burrito-joint version often found languishing on steam tables. We set out to perfect the methods that give tinga (pronounced teen-GA) its characteristic crisp texture and smoky tomato flavor. We wanted tender, full-flavored Mexican shredded pork that we could serve atop crisp corn tortillas or spoon into taco shells.

We trimmed and cubed a Boston butt (chosen for its good marbling and little sinew), then simmered the pieces in water that we flavored with garlic, thyme, and onion. Once the pork was tender, we drained the meat (reserving some of the cooking liquid for the sauce) and returned it to the pot to shred. The meat was so tender, it fell apart with nothing more than the pressure of a potato masher. We then sautéed the meat in a hot frying pan along with the requisite additions of finely chopped onion and oregano. Minutes later, the pork had developed crackling edges crisp enough to survive the final step of simmering in tomato sauce. Unlike American barbecue with its sweet and tangy barbecue sauce, tinga relies on a complex smoke-flavored tomato sauce. For our version, we diluted canned tomato sauce with the reserved flavorful cooking liquid from the pork and added bay leaves for herbal complexity. And for tinga's all-important smokiness, we turned to ground chipotle powder, which is a little harder to find than the other option of canned chipotle chiles in adobo sauce, but is has a deeper, more complex flavor.

Serves 4 to 6

The trimmed pork should weigh about 1 1/2 pounds. Tinga is traditionally served on tostadas (crisp fried corn tortillas), but you can also use the meat in tacos and burritos [and enchiladas] or simply served over rice. Make sure to buy tortillas made only with corn, lime, and salt—preservatives will compromise quality. Our winning brand of ready-made tostadas, Mission, is also an excellent choice. We prefer the complex flavor of chipotle powder, but two minced canned chipotle chiles can be used in its place. The pork can be prepared through step 1 and refrigerated in an airtight container for 2 days. The tostadas can be made up to a day in advance and stored in an airtight container.

2 pounds boneless pork butt, trimmed of excess fat and cut into 1-inch pieces (see note above)
2 medium onions, 1 quartered and 1 chopped fine
5 medium garlic cloves, 3 peeled and smashed and 2 minced or pressed through garlic press (about 2 teaspoons)
4 sprigs fresh thyme
table salt
2 tablespoons olive oil
1/2 teaspoon dried oregano
1 (14.5-ounce) can tomato sauce
1 tablespoon ground chipotle powder (or 2 minced canned chipotle chiles)
2 bay leaves
table salt

3/4 cup vegetable oil
12 (6-inch) corn tortillas

Garnishes
queso fresco or feta cheese
fresh cilantro leaves
sour cream
Diced avocado
Lime wedges

1. FOR THE TINGA: Bring pork, quartered onion, smashed garlic cloves, thyme, 1 teaspoon salt, and 6 cups water to simmer in large saucepan over medium-high heat, skimming off any foam that rises to surface. Reduce heat to medium-low, partially cover, and cook until pork is tender, 75 to 90 minutes. Drain pork, reserving 1 cup cooking liquid. Discard onion, garlic, and thyme. Return pork to saucepan and, using potato masher, mash until shredded into rough ½-inch pieces (see Step-by-Step below); set aside.

2. Heat olive oil in 12-inch nonstick skillet over medium-high heat until shimmering. Add shredded pork, chopped onion, and oregano; cook, stirring often, until pork is well browned and crisp, 7 to 10 minutes. Add minced garlic and cook until fragrant, about 30 seconds.

3. Stir in tomato sauce, chipotle powder [or 2 minced canned chipotle chiles], reserved pork cooking liquid, and bay leaves; simmer until almost all liquid has evaporated, 5 to 7 minutes. Remove and discard bay leaves and season with salt to taste.

4. TO FRY TOSTADAS: Heat vegetable oil in 8-inch heavy-bottomed skillet over medium heat to 350 degrees. Using fork, poke center of each tortilla 3 or 4 times (to prevent puffing and allow for even cooking). Fry 1 at a time, holding metal potato masher in upright position on top of tortilla to keep it submerged, until crisp and lightly browned, 45 to 60 seconds (no flipping is necessary). Drain on paper towel-lined plate and season with salt to taste. Repeat with remaining tortillas.

5. TO SERVE: Spoon small amount of shredded pork onto center of each tostada and serve, passing garnishes separately.

Technique

Crisp-Tender Mexican Shredded Pork

1. SIMMER AND DRAIN
Simmer pork with aromatics to infuse with vegetal flavors. Drain, reserving 1 cup of liquid.
2. SHRED
Mash pork with potato masher to maximize surface area for browning.
3. SAUTÉ AND BRAISE
Cook pork with onions and oregano until exterior is deeply brown and crisp, then simmer in sauce.