Chicken Breast Sandwich, Onions, Watercress, Paprika Aioli

Ingredients

• 1/2 cup mayonnaise
• 1 tablespoon fresh lime juice
• 1 teaspoon hot spanish smoked paprika
• 1 garlic clove, pressed
• 2 tablespoons extra-virgin olive oil, plus more
• extra-virgin olive oil, for brushing on roll
• 2 tablespoons vegetable oil
• 2 lbs onions, halved lengthwise, thinly sliced crosswise (about 7 cups)
• 3 boneless skinless chicken breast halves, cut crosswise in half (8 oz each)
• 6 sourdough rolls
• 3 cups lightly packed watercress or arugula

Directions

1. 1

   Whisk mayonnaise, lime juice, Spanish paprika*, & garlic in small bowl.

2. 2

   Gradually whisk in 2 tablespoons olive oil.

3. 3

   Season with salt and pepper.

4. 4

   Aioli can be made 2 days ahead; cover prepared aioli and chill.

5. 5

   Heat vegetable oil in heavy large skillet over medium-high heat.

6. 6

   Add onions, sprinkle with salt, and cook until beginning to brown, stirring often, about 10 minutes.

7. 7

   Reduce heat to medium and continue to cook until onions are soft and deep golden brown, stirring often, about 20 minutes longer.

8. 8

   Season with salt and pepper.

9. 9

   Onions can be made 2 hours ahead; let stand at room temperature.

10. 10

    Prepare barbecue (medium-high heat).

11. 11

    Place chicken breasts between 2 sheets of plastic wrap.

12. 12

    Pound with mallet to 1/3-inch thickness.

13. 13

    Sprinkle with salt and pepper.

14. 14

    Grill chicken until cooked through, about 3 minutes per side.

15. 15

    Transfer to work surface.

16. 16

    Brush cut side of rolls with extra-virgin olive oil.

17. 17

    Grill rolls, cut side down, until grill marks appear, about 1 minute.

18. 18

    Spread rolls with some of aioli.

19. 19

    Assemble sandwiches, dividing chicken, caramelized onions, and watercress among rolls.

20. 20

    Serve warm.