Cut 4 baby bok choy in half lengthwise; place in large bowl. Drizzle with soy sauce and sesame oil; toss to coat. Arrange bok choy on a grill rack coated with cooking spray; cook in oven on 400 2 minutes on each side or until leaves begin to brown. Return bok choy to bowl; cover with plastic wrap. Let stand 3 minutes or until tender. Sprinkle evenly with 1/4 teaspoon salt.