Roughly dice onions. Heat oil in the large pot and soften onions. Add the coriander, cumin, turmeric, lemongrass, ginger and garlic and fry for about 1-2 minutes.
Add beef and fry in the spice mix until sealed/browned.
Dissolve beef stock in 1 ½ cups of water. Add beef stock, coconut milk and desiccated coconut to the mix and bring to a slow boil.
Simmer for about 4-5 hours. Over this time ensure the mix doesn't dry out.
Once the meat is tender and the sauce reaches the desired consistency, season to taste with salt and then it is ready!
Notes
Not true to authentic rendang but this is how my family has made it for years.
Great with lime leaves as well. If adding, add them in before you simmer for 5h.