4 teaspoons olive oil, divided
2 cups sliced leek
4 garlic cloves, minced
1/3 cup all-purpose flour (about 1 1/2 ounces)
1 pound skinless, boneless chicken thighs, cut into bite-sized pieces
1/2 pound skinless, boneless chicken breast, cut into bite-sized pieces
1/2 teaspoon salt, divided
1/2 teaspoon freshly ground black pepper, divided
1 cup dry white wine
3 cups fat-free, less-sodium chicken broth, divided
1 tablespoon all-purpose flour
1 1/2 cups water
2 tablespoons Dijon mustard
2 cups (1/2-inch) cubed peeled white potato (about 1 pound)
8 cups loosely packed torn kale (about 5 ounces)
Crushed red pepper (optional)