Belgium's national dish _ golden-brown fried potato sticks sprinkled with salt and covered under a blob of mayonnaise _ is getting healthier again. The consumer group Test-Achat said Wednesday new legal standards for frying fats, which came in the wake of a damning 1987 report on Belgium's unhealthy ``frites,'' have done the trick. ``The statistics indicate a considerable improvement over three years ago,'' Test-Achat said in its magazine.