Massage The Kale: Fold each kale leaf in half lengthwise, then pull out and discard the center rib. Tear leaves into bite-sized pieces and place in a large nonreactive bowl (you should have about 6 cups).
Add lemon juice and salt to kale and, with clean hands, rub and gently squeeze the kale until it just begins to soften and wilt (it will darken in color). Add orange juice, vinegar, and oil and toss to coat and set aside while you prepare the rest, at least 10 minutes.
Toast The Pepitas: Meanwhile, toast the pumpkin seeds in a dry cast iron skillet over medium heat. When golden brown, add a drizzle of olive oil and the chile powder and cook until fragrant. Toss to coat then remove from heat.
Plate The Salad: Taste the kale and add more salt or vinegar, as desired. Divide salad among plates, add avocado, mango, and cheese, sprinkle each with a spoonful of seeds and serve.