Melt butter in a medium, heavy saucepan. Add corn kernels and saute over medium-high heat for 2 minutes. Remove corn from pan. Add water and salt and bring to a boil; gradually whisk in grits. Reduce heat and simmer, uncovered, 20 to 25 minutes or until thick, stirring often. Stir in corn, chives, sugar and pepper.
While grits are cooking, sprinkle pork with salt and pepper. Heat 1 tablespoon oil in a large skillet over medium-high heat; add half of pork and cook 2 to 3 minutes on each side or until browned. Remove from skillet; repeat with 1 tablespoon oil and remaining pork.
Add remaining 1 tablespoon oil to skillet and heat; add mushrooms and cook over medium heat 5 minutes. Add broth and next 4 ingredients, stirring to loosen particles from the bottom of skillet. Combine cornstarch and 2 tablespoons water, stirring until blended. Add cornstarch mixture to skillet and bring to a boil. Cook 1 minute or until thick and bubbly, stirring constantly. Return pork to skillet; serve pork mixture over Two-Corn Grits.