Heat gas or charcoal grill. In large bowl, mix 1/2 cup of the yogurt, the curry powder, paprika and garlic salt. Add chicken, stirring to coat all surfaces. Let stand 15 minutes.
Meanwhile, in small bowl, mix remaining yogurt and remaining ingredients.
Place chicken on grill. Cover grill; cook over medium heat 8 to 12 minutes, turning once or twice, until juice of chicken is clear when thickest part is cut to bone (180°F). Serve with yogurt dip. Sprinkle dip with additional chopped fresh mint leaves if desired.