In a medium bowl, combine the sour cream, salsa, cilantro, and 1 teaspoon taco seasoning; mix well. Cover and chill until ready to serve. In a large bowl, toss the chunks of Chicken or Beef with the remaining taco seasoning; mix well. Coat a large nonstick skillet with nonstick cooking spray. Heat over medium-high heat. Add the Chicken or Beef chunks and sauté for 6 to 8 minutes, or until desired doneness. Skewer each piece and place on a serving platter; serve with the salsa dipping sauce. Garnish with cilantro sprigs.