To prepare the kale, first remove the tough ribs with a chef’s knife and discard them. Chop the kale into small, bite-sized pieces. Sprinkle it lightly with salt, followed by a squeeze of lime juice (about 1 teaspoon). Massage the kale by scrunching it up in your hands, repeating until the kale is darker green and fragrant (this step softens the kale and makes it less bitter). You’ll need 1 cup (packed) kale for the guacamole, so measure it out and set it aside.