Unexpected reactions to toast

The scenario: Little man is sitting at his breakfast bar (there's only room for one stool) with a cup of milk and bowl of cereal. Mummy is making toast. As she starts buttering it, little man says 'toh, toh'. Mummy says: 'You'd like some toast?' Little man nods. Mummy puts a couple of triangles of toast on a plate for little man and puts them in front of him. Little man wails. Clearly, mummy has done something wrong. She takes the toast away. Little man says 'toh, toh', reaching out his hand towards my plate. I offer him my plate and let him choose a piece of toast. He takes one and eats it.

Then there were the lunch choices:
'Would you like some soup?' (Red lentil, diet fare but tasty. Rejected by the boy, however, the day before.)
'No.'
'Would you like some cheese on toast?'
'No.'
'Would you like some beans?'
'No.'
In the end I gave him some oatcakes, cheese and tomatoes, which he picked at. I don't know how much oatcake ended up in his cup of water because he did it after I'd finished my lunch and was tidying the kitchen.

This evening he picked all the crispy bits off some potato wedges and ate only those bits. He kept biting bits off the mini sweetcorn and chewing them up. Then spitting them out.

I am struggling with the toddler psychology. The wrong-plate-colour tantrums. The getting-set-in-his-ways desire for oatcakes every day.