A bit random, but I hope that this helps you....
We adopted an "assembly" method. I found that if I put dishes on the table of grilled vegetables, strips of chicken, cheese cubes etc that my DS would eat pretty much anything into a tortilla and wolf it down-then proceed to make another one.
Makes for messy mealtimes, but the upshot is that he now consumes all the food groups I'd been desperate to get into him and with a little encouragement, mealtimes are pretty much stress free.
Mini pitta breads, baked potatoes, toast slices, small chops and "eat with your hands" type stuff (chicken drumsticks and similar) also worked.
We have now progressed to a stack of kebab skewers and "fun foods" (cherry tomatoes, brocolli spears, cheese, chicken courgettes etc) for him to choose and assemble this way.
A bit of planning yes, but damn it's a relief when he will actually eat proper foods.
Best of luck- I hope that this is of some help to you??