Showing that you "don't care" works, as mentioned above...esp when dinner is literally thrown in your face.
And thanks to your advice tonight ladies, we did exactly that. Cooked the roast, put DD's plate down in front of her and she immediately asked for yoghurt. Answer was no. Tantrum. I asked her if she wanted her dinner, she asked to 'get down' so we got her straight out of her highchair. She stood there for a minute, then walked back to the table, took a handful of pumpkin and ate it!!!! We put her back in her high chair and she ate three large pieces of pumpkin!