Ideas for sandwiches (toddler)

[user1471523870]

My two year old recently discovered sandwiches, which is great as he used to want only toast until few weeks ago!

So far I successfully tried only gam and cheese or ham and cucumber (both with butter spread on one slice.
He's allergic to egg, nuts and sesame seeds, which is tricky for fillings ...
I want to try tuna, vegan Mayo and sweet corn. Possibly chicken or turkey with vegan Mayo and a lettuce leaf?

Ideas?

My boys liked luncheon meat, cheese, ham, turkey and chicken. They didn’t like tuna or salmon until they were older. One liked pickle and the other liked lettuce and cucumber, neither liked tomatoes.

Soft cheese with cucumber
Salmon and cucumber
Salmon and soft cheese
Avocado and tomato
Any mix of salad items (with mayo or pickle)

Cream cheese with grated carrot
Toasted cheese sandwiches with grated mushrooms in
Sardines mashed into cream cheese
Mashed avocado and a little bit of chopped bacon