To prep steak, whisk together marinade ingredients (the coconut milk through the chili sauce) in a large bowl. Season the steak with salt and pepper then add to a large baking dish or ziplock bag. Pour marinade over top and refrigerate for 2-24 hours.
To make the dressing, preheat the oven to 400 degrees F. You can do this ahead of time or right before you make the steak if you choose to use the oven. Place chopped mango, chili powder and teaspoon of olive oil on a baking sheet and toss. Roast for 20 minutes until just golden and caramely.
In the bowl of your food processor (or blender), add roasted mango, lime juice, vinegar and a sprinkle of salt and pepper. Stream in olive oil with the processor going until the dressing comes together. This can be stored in the fridge for a few days.
When you’re ready to make the salads, cook the steak however you’d desire – I either grill it or broil it. To broil, I place the rack directly underneath the broiler. The steak is usually slightly less than 1 inch thick, so I broil about 5 minutes per side for medium to medium-well steak. Let it rest before slicing against the grain into strips.
To assemble the salads, combine greens with mango, onions, cilantro and sprinkle of salt and pepper. Add steak and cashews over top, then drizzle on dressing.