I'd probably go for finger foods at lunchtime if he's having porridge / puree the rest of the time so he gets used to the different textures. They need to be an 'easy to pick up' sort of size. Maybe slices of toast / pitta and individual pasta swirls as carby options? Cubes of cheese and ham? Various 'crudite' type vegetables like cucumber, carrot and pepper slices? Also chunks of fruit like banana, apple and pear?