Andouille & Beef Burgers with Spicy Mayo & Caramelized Onions

Ingredients

• ¾ cup mayonnaise
• 1 tbsp fresh lemon juice
• 1 tsp Cajun or Creole seasoning blend
• ¼ tsp hot pepper sauce
• ½ lb andouille sausage, cut into scant 1/4-inch cubes
• ¾ cup pecans, toasted, chopped
• 1 tsp salt
• ¼ tsp ground black pepper
• 1 1/2 lbs ground beef chuck or ground beef (20 percent fat)
• 1 ½ lbs onions, thinly sliced
• 2 tbsp olive oil plus more for brushing grill rack
• 3 garlic cloves, minced
• 1 tbsp golden brown sugar
• 6 large hamburger buns, split
• 8 oz crumbled blue cheese
• 12 pickled okra pods, halved lengthwise*
• 3 cups watercress tops