First off, no avocado with the salmon! Both are oily and strong tasting, so I really can't see that going well.
Just so I'm sure, your brief is this:
3 course meal, and within those three courses you need to use the 5 mandatory ingredients, but they can be used in any dish.
That's correct right? That's the brief I'll comment on, but please feel free to refine it if I've misunderstood something.
My thoughts would be this:
Arugula & mozzarella salad with a reduced balsamic & lemon dressing
Confit salmon with chilli & mascarpone linguine
Strawberry & Italian meringue mille feuille
Doing this would allow you to show off numerous techniques and skills without putting the flavours of garlic, strawberry, avocado and salmon all in the one dish, which I would REALLY worry about.