Best New Age Chicken Macaroni Salad

Name: Best New Age Chicken Macaroni Salad
Ingredients: FOR THE DRESSING; 1 cup mayonnaise; Juice of 1 lemon; 2 tablespoons Worstershire Sauce; 1 generous tablespoon whole-grain Dijon mustard; FOR THE SALAD; 1 yellow onion, halved, peeled, 1/2? slices; 4 chicken thighs or 2 chicken breasts, bone-in or boneless; Olive oil; Sea or kosher salt and grinds of pepper; 1 pound ditalini or elbow macaroni, cooked, drained, cooled in cold water; 4 ribs celery, 1/4? dice; 1 orange or red bell pepper, 1/4? dice; 15 ounce can pineapple tidbits, drained; 2 tablespoons fresh tarragon, minced; 2 teaspoons sea or kosher salt; 12 grinds of pepper; 2 pinches red pepper flakes