Place potatoes in a saucepan; cover with water. Bring to a boil. Reduce heat, and simmer 15 minutes or until tender; drain. Cool.
Combine parsley and the next 6 ingredients (through black pepper) in a large bowl, stirring well; stir in 1/4 teaspoon salt. Add potatoes, bell pepper, okra, shallots, beef, and squash; toss well to coat. Cover and chill 1 hour.
Thread vegetables and beef alternately onto each of 8 (10-inch) skewers. Sprinkle kebabs evenly with remaining 1/4 teaspoon salt. Place kebabs on grill rack coated with cooking spray; grill 10 minutes or until desired degree of doneness, turning occasionally.