Peel and core the pears and cut them in half. Combine the boiling water and the syrup and poach the pears 20 minutes in the mixture. Remove the pears from the water and drain them. To serve, spoon some of the yogurt onto each of 12 glass plates. Place one pear half, cut side down, on each plate and garnish with a sprig of mint and dust with a little nutmeg.