Another fussy one here too (aged 8). He eats a hugely varied diet of bread, cereal, bread, grapes, bread, salad (all types, bizarrely), bread, veg (so long as it's raw), bread, plain pasta, bread, baked beans. And did I mention bread?
I make no fuss at all in the certain knowledge that he will one day branch out into, ooh, pasta with sauce. Though I have to say I am really, genuinely not that worried - which makes it easier not to convey worry (IYSWIM).
Forkhandles, we have exactly the scenario you describe. ("If I just put our family meal in front of him he would just say he didn't want it and ask for a sandwich. How do you ignore or not notice that?") What I do is say: no, you can't have a sandwich. This is what's on offer; you can either eat it or leave it, but there's nothing else. I try to provide, eg, raw carrot/tomatoes so there's something that he can at least nibble at. If he leaves his meal, I remove it without comment. He has no snacks between meals.
As pudding is fruit, there's no mileage in the 'you can have pudding if you eat your first course' thing. Plus I wouldn't want to turn pudding into a big treat anyway.
I figure that if I keep putting the same things on the table, he will eventually try them. It apparently takes something like 50 attempts before a fussy child will eat something new. We all eat together, and always have done, so he's seen mealtimes as pleasant (when not being nagged about table manners by DH) occasions rather than all about food. DD eats anything, so I don't think we've done anything much wrong. It's just the way he is, and he'll grow out of it eventually.