Boil potatoes in water till done. Cool, pat dry and smash to form flat disks.
Mix all the marinade ingredients in a bowl and add potatoes and capsicum. Coat evenly and leave to marinate for 30 minutes.
Heat oil in a skillet to shallow fry potatoes till crispy on the outside. Remove and keep aside and stir fry capsicum in the same oil. Remove and keep aside. SAVE the remaining marinade.
Transfer 1 T of same oil into another pan and add cumin seeds, ginger, tomato puree, turmeric, tikka masala spice and sugar. Cook stirring for 5-7 minutes.
Add the remaining marinade into the pan and water if required. Bring to a simmer and add capsicum and potatoes.
Stir in oat cream, vegan butter and fenugreek seeds. Season as required.