Caramelize the sliced onion in 1 tablespoon olive oil over low to medium heat (for instructions, see TIP B below). Lay the bread slices flat on a baking sheet that has been brushed lightly with olive oil. Toast the bread in a pre-heated 450° oven for 6-8 minutes or until golden brown on both slides (flip once while toasting). Remove the toasted bread from the oven and arrange on a plate or serving dish. Spread a thin layer of Major Grey mango chutney over each piece of toast. Top each toast with arugula leaves, caramelized onion, and a generous mound of chicken salad. Finish with a sprinkle of kosher or coarse ground sea salt and fresh ground pepper.
TIP A: This recipe is what store-bought rotisserie chickens were made for, but don't cut corners on freshness or quality. I'm a big fan of the Whole Foods® Market rotisserie chickens (particularly on Tuesdays when they go on sale at my local market—wink, wink). They're always, fresh, lean, juicy, and flavorful.
TIP B: Low and slow is the key to perfect caramelized onions. Set your burner to medium-low and let 1 tablespoon of olive come up to temperature before adding the onion. Spread the thinly sliced onion pieces evenly around the pan and let the heat and natural sugars of the onion do their thing! Stir occasionally and cook approximately 40-45 minutes or until the onion slices are evenly golden brown and almost jam-like in consistency. Sprinkle with a pinch of kosher salt if needed.