Pre-heat the oven to 180ºC. Oil a 23 cm round baking pan.
Heat a large skill let over medium heat. Add 3 tablespoons of vegan margarine, pears, sugar, and cinnamon, and cook, covered, for 5 to 10minutes, or until the pears are tender and slightly caramelized. Let the cooked pears cool to room temperature. Transfer the pears and their syrup to the prepared pan, spreading evenly.
In a large bowl, combine the buckwheat and white rice flours, powdered ginger, ground cinnamon, salt and baking powder.
In another large bowl, whisk the melted vegan margarine and sugar. Add the yoghurt, soy milk, and agave nectar to the mixture, stirring to combine.
In a medium-sized bowl, add the gram flour and water, whisking everything until you get a smooth consistency. Slowly pour this mixture over the wet mixture and combine well.
Using a rubber spatula, fold the wet mixture into the dry mixture, being careful not to overmix.
Pour the batter into the prepared pan – over the pears- and bake for 40 to 45 minutes, or until a toothpick inserted in the center of the cake comes out clean.
Cool the cake in the pan for 20 minutes before inverting onto a large plate.