Chicken and Fennel Stew

Name: Chicken and Fennel Stew
Ingredients: For the stew; 3 tablespoons olive oil; 1 large leek (white and light green only)sliced lengthwise and then crosswise into 1/4 inch half moons; 4 cloves garlic, minced; 1 teaspoon fennel seeds, crushed a bit; 2 bulbs fresh fennel (save a few fronds for garnish) sliced; 2 pounds boneless, skinless chicken thighs, trimmed of any excess fat and the cut into 1 to 2 inch pieces; 1 14 to 15 ounce can of plum tomatoes; 1/2 cup dry white wine; 2 1/2 cups chicken broth; 4 medium potatoes, peeled and cut into 1 to 2 inch pieces.; Salt and pepper to taste.; For the rouille; 2 pieces of potato from the stew; 3 to 4 tablespoons of the stew's broth; 2 cloves minced garlic; 1/8 teaspoon cayenne pepper (optional); 1/2 cup mayo