Heat 2 teaspoons vegetable oil in a frying pan or curry pan over a medium head. Add 1 small onion, roughly chopped and 1/2 green pepper, roughly chopped. Stir-fry for 2 minutes.
Add 80 millilitres curry broth, 1 teaspoon garlic ginger paste, 1 fresh green finger chilli, thinly sliced, 1 teaspoon tomato puree, 1/4 teaspoon mild red chilli powder, 1 teaspoon dried fenugreek leaves (methi), pinch sea salt, 1 small handful fresh coriander leaves, finely chopped. Mix well, bring to the boil and add another 80 millilitres curry broth and 1 portion cooked chicken for curry dishes. Simmer for 2 minutes.
Add the remaining 80 millilitres curry broth, 1 teaspoon ground almonds, 2 tablespoons tomato ketchup, 1 teaspoon mango chutney, 1 heaped teaspoon mixed pickle, 50 millilitres single cream and 1 teaspoon fresh lemon juice or lemon dressing. Mix well and simmer for 2 minutes or until the achari curry sauce is slightly thick and bubbling hot.
Transfer the chicken achari curry to a serving bowl and finish with a little more fresh coriander. Serve with your favourite Indian rice and breads.