1. Melt 2 tablespoons butter in a Dutch oven over medium-high heat. Sprinkle shrimp and fish with 1/4 teaspoon salt. Add half of seafood to pan and cook, turning once, 3 to 4 minutes or until browned. Repeat with remaining seafood. Transfer to a bowl; cover and keep warm. Set aside.
2. Add remaining 2 tablespoons butter to Dutch oven over medium-high heat. Add onions; cook 7 to 8 minutes or until golden brown, scraping to remove browned bits from bottom of pan. Stir in cumin and next 3 ingredients; cook, stirring constantly, 15 seconds or until fragrant. Stir in tomatoes and next 3 ingredients, and cook 1 minute. Stir in rice and cloves, and cook, stirring constantly, 1 minute.
3. Stir in 2 cups water and remaining 3/4 teaspoon salt. Bring to a boil, reduce heat to medium-low, and simmer 17 to 18 minutes or until liquid is absorbed. Stir in reserved seafood until heated through. Sprinkle with cashews.