To prepare sauce, combine first 6 ingredients in a bowl; stir with a whisk.
To prepare shrimp, combine cumin, paprika, coriander, garlic powder, salt, and black pepper in a medium bowl. Add shrimp; toss well. Heat 1 1/2 teaspoons oil in a large nonstick skillet over medium-high heat; add half of shrimp. Cook 3 minutes on each side or until done. Remove shrimp; keep warm. Repeat procedure with remaining oil and shrimp. Serve shrimp with sauce. Garnish with cilantro, if desired.