1Heat oven to 375°F. Prick potatoes with fork. Bake potatoes 1 hour to 1 hour 15 minutes or until tender. Let stand until cool enough to handle, about 30 minutes. Cut potatoes lengthwise into halves; carefully scoop out pulp, leaving 1/4-inch shells. Cut each potato shell into 2 wedges.
2In small bowl, mash avocado; add yogurt, garlic, cilantro, 1/2 teaspoon of the grill seasoning and the lime juice; mix well.
3Top each potato wedge with about 1 tablespoon avocado mixture and slice of beef; sprinkle tops with remaining 1 teaspoon grill seasoning. Garnish with tomato wedge and, if desired, cilantro sprig.