Remove a small portion of the raw mince and set it aside (less than quarter of the full amount). We'll use this later on.
Put the remaining mince directly into a pan, and add some coriander, garam masala, dhana jeera, cumin powder, turmeric, salt, ginger/garlic, green chillies and some of the lemon.
Place the pan on medium heat and dry the mince, keep stirring the mixture regularly so that it it's evenly cooked and doesn't form lumps. Once it's totally dry (when you notice it starting to stick to the bottom of the pan) spill the mixture into a bowl and set it aside for a while. Using the same pan, put the butter, heat it a little, then add the grated onions and black pepper and stir fry them until the onions soften.
Pour back the dried mince into the onions n stir thoroughly on low heat. Taste and adjust salt/pepper/lemon according to your taste. Switch off and let the mixture cool.
Once the mixture is completely cool, add the raw mince you had set aside earlier, gram flour, egg, the soaked n drained bread (make sure you squeeze out as much of the water as you can from the bread). Mix together and lastly (right before baking/grilling) add a quarter tsp. of baking soda (helps soften the patties).
Shape into flat circles/patties, place on a greased tray and bake. Make sure to turn the patties midway through cooking so that both sides get done evenly. Take care whilst turning them so that they don't break. If you try to turn the patties and they are stuck, give them some more time to bake then try again. Once the under-side is done they will turn easily. Be gentle during turning. Also make sure you put the tray into the oven whilst it's at its hottest temp (around 200C), then reduce the heat within 5mins to about 170 C and continue on a lower heat the rest of the way through. This helps retain moisture in the patties so they don't become dry. They will take about 15-20 mins to be done on both sides. You can pat the patties with a teeny blob of butter once they are done, right from the oven...to give them a nice buttery flavor, then use them immediately or set them out to cool and store for whenever you crave a burger.
I normally like adding about a handful of SHAMI KABAB mixture to this burger patties mixture. It helps level/flatten the surface of the patties and gives it a nicer taste, but is entirely optional.