This might seem a little obvious but when I first went vegan I thought there would be nothing I could put in a sandwich because cheese and cold meats were not an option and my lunches would be forever more difficult. I was wrong. There are many options:
Humous, falafel and spinach make the perfect combo.
Grated carrot also works well here.
Spoon on some humous and add some spinach leaves.
Crumble on some raw tofu and season with salt, pepper, and Paprika.
Add a splash of soya sauce and drizzle of Agave/ Maple syrup.
If you have any leftover roast vegetables these make a great next-day sandwich (or bagel filling) especially when paired with some spicy tomato sauce.
Lightly toast some bread and slice some vegan cheese on one slice and put under the grill to melt the cheese.
For when you want to be a child again.
Remember you can get cheese and meat alternatives in health food stores to help with any cravings. My soft spot is pate and luckily Holland and Barretts stock some.