Preheat the oven to 200°C, fan 180°C, gas 6. Heat half the oil in a frying pan and cook the chicken for 5 minutes, until golden. Stir in the spice blend and cook for 1 minute. Remove from the pan; set aside.
Wrap the tortillas in foil and warm in the oven for 8 minutes.
Meanwhile, heat the remaining oil in the pan and cook the onion and peppers for 5 minutes, then stir in the passata. Return the chicken to the pan along with the mixed pulses. Cook, stirring, for a further 2-3 minutes, until the chicken is cooked through and no pink remains. Stir in the chopped coriander.
Serve the tortillas topped with the chicken mixture, some soured cream and grated Cheddar. Garnish with the reserved coriander, and serve with the salad.