Bring a large pan of salted water to the
boil. Simmer the marrow for 5-7 mins
until softened, then drain well. Heat the
oil in a large shallow pan and fry the
mustard and cumin seeds until they start
to crackle. Add the onion, garlic and
remaining spices, and fry for 10 mins
until soft and starting to brown. Add
the marrow and cook for 5-10 mins
until the liquid has evaporated and the
marrow is really soft.
Smash the marrow with a wooden
spoon to lightly crush and soften the
edges. Serve seasoned with the lemon
juice and chopped coriander.