Thai Beef Satay with Peanut and Cucumber Sauce

Name: Thai Beef Satay with Peanut and Cucumber Sauce
Ingredients: bamboo or metal skewers; 2 pounds flank steak or london broil, cut into strips or cubes.; 1/2 cup sliced onions, large slices; 2 tablespoons canola oil; 2 tablespoons butter; 1 tablespoon curry powder; 2 teaspoons coriander powder; 2 teaspoons sugar; 1 tablespoon fish sauce; 1/2 cup water; 1/3 cup peanut butter, smooth or chunky; 1 garlic clove, minced; 1 tablespoon brown sugar; 1 1/2 teaspoons soy sauce; 1/8 teaspoon crushed red pepper; 3/4 teaspoon lemon juice; 1/2 cup white vinegar; 1/2 cup sugar; 1 teaspoon salt; 1 cucumber, diced; 1/3 cup purple onion, diced; 2 tablespoons chopped peanut, unsalted and roasted