Finely grate or slice the papaya and mango into long, thin strips. Combine the mint and basil leaves in a large salad bowl with the mango and papaya. Finely slice the shallots and add them to the mixture.
Make the dressing. Crush the chilli with the ginger and sugar using a pestle and mortar. Add the lime juice and fish sauce to taste.
Heat a griddle pan on a high heat, add the oil and fry the steak for 5 minutes on each side. Remove the steak from the pan and leave it to rest for 5 minutes.
Thinly slice the steak diagonally and arrange neatly on the serving plates. Add the dressing to the salad, mix well to combine and serve with the steak.