To poach mandarins, heat juice, zest, sugar, thyme and spices in a medium saucepan over a medium heat. Place mandarin halves and cook for 5 minutes. Remove from heat and cool in syrup.
Using a slotted spoon transfer the poached mandarins to a bowl. Place saucepan over a medium-high heat and bring to a simmer. Cook for 5 minutes, or until liquid reduces by half and becomes syrupy. Remove from heat.
To make porridge, place oats and 750ml of milk or water in a medium saucepan set aside for 30 minutes to soak the oats. (if time allows soak the oats over night, cover and leave in refrigerator overnight) When ready to cook, place saucepan over a medium heat and bring to a simmer. Reduce heat to low and cook for 5 minutes stirring occasionally, add the salt and remaining milk or water and continue to stir for another 2 minutes or until porridge is a creamy thick consistency.
Ladle porridge into serving bowls. Top with poached mandarin and drizzle over syrup. Spoon a dollop of yoghurt and dust with cinnamon. Serve immediately.