To prepare vinaigrette, place lemon juice, vinegar, mustard, honey, salt and black pepper in a food processor fitted with the swivel blade. Begin processing, slowly pouring in oil.
To prepare salad, place kale leaves in stacks, and cut crosswise into 1/2-inch ribbons. Cut ribbons into bite-sized pieces.
Place kale, apples, onion and toasted pumpkin seeds in a large bowl. Pour in about half the dressing and toss gently. Serves 10.