Combine tuna, olives, green onions and celery in medium bowl. Combine Pace Picante Sauce, sour cream and cumin; mix well. Pour over tuna mixture; toss lightly. To serve, line taco shells with lettuce leaves; spoon tuna mixture into shells. Or, line individual serving plates with shredded lettuce; top with tuna mixture and surround with tortilla chips. Drizzle with additional Pace Picante Sauce; top with additional sour cream, if desired.