Bombay chilli cheese toastie

Name: Bombay chilli cheese toastie
Cook time: 30 min
Total time: 30 min
Cuisine: Indian
Ingredients: potatoes 300g, boiled until tender, peeled and diced; chaat masala 1 tsp (see cook’s notes below); green pepper ½, finely chopped; red onion ½, finely chopped; soft white bread (a farmhouse loaf or bloomer is good for this) 8 slices; butter softened; emmental 8 slices; pistachio kernels 1 tbsp, soaked in just-boiled water for 20 minutes; mint leaves 100g; coriander leaves 50g; lemon ½, juiced; green bird’s-eye chilli 1, (add 1 more if you like it spicy); red onion ¼, finely chopped; ginger 3cm chunk, chopped; caster sugar a pinch