Just a few things to remember, rinse the lentils thoroughly, chop the sweet potato finely (evenly doesn't matter so much as in the cooking time it'll all work out alright) and don't overcook the onions, nice and soft, not all crispy and brown.
Now I'm not going to post a step by step here, as the instructions on the site I took the recipe from are excellent, and the proportions are excellent, and it is in fact just generally excellent.
So bear in mind my tips, make this http://goo.gl/vSWX and enjoy it!
Feel free to contact me if you have any issues as well, I'm here to help :)
And a quick snap, an expect another post later this evening.