Combine yeast & water & let stand for 10 minutes. Stir in oil & thyme, followed by potatoes, honey & soymilk. Stir gently till mixture is smooth.
In another bowl, combine flours, cornmeal & salt. Make a well in the centre & pour in wet mixture. Mix together, then knead in a floured bowl for 10 minutes. Let rise, covered till doubled in bulk. Punch down dough & divide into 6 pieces. Roll each piece into a long coil with hands, about 3 cm in diameter. To make each loaf, braid 3 coils & pinch ends together.
Place on a floured baking sheet, cover with damp cloth & let rise till doubled in bulk. Brush tops with soymilk & bake in a preheated 180ºC for 40 to 50 minutes, till tops are golden.