Wash and peel the potatoes, cut into dice and boil until soft (so a knife goes all the way through.
Finely chop the red onions, ginger and chillies.
Wash, peel and grate the beetroot.
In a pan, over medium heat, add the olive oil and black mustard seeds.
Once the seeds start to pop, add the onions and ginger and fry unitl soft.
Add the green chillies to the onion-ginger mix, then add the beetroot. Season with salt.
Cook the beetroot mix over medium heat until the mix is almost dry. Then finish with the amchur powder. Mix and take off the heat and set aside to cool.
Drain the cooked potatoes and mash.
Portion the mashed potatoes into 12 individual portions.
Roll each portion of mashed potato into a ball and then press down in the centre to form a cavity. Add a spoonful of the cooled beetroot mix into the centre of the mashed potato. Bring all the sides together towards the centre and form a ball with the beetroot mix enclosed within. Press down flat and hold between your thimb and finger to shape into a round medallion.
Once all of the patties are shaped, you can stop here and refrigerate the mix for a couple of hours or overnight if you want the red colour.
To fry the patties, coat in semolina and pan fry on both sides over medium heat for about 2 minutes.
To assemble the burger, cut the brioche buns in half. Coat the bottom of one half with sonth chutney. Then place the cooked patty topped with coriander chutney and pickled onion. Secure the top with a toothpick and serve hot.