Spread both slices of bread liberally with hummus and set aside.
Slice the avocado in half, twist, and set one half aside. Run your knife across the avocado half just down to the skin to make thin slices. Cut it in half again and peel back the skin to free those green delicious pieces. Layer them on one slice of bread in an amount that suits you.
Slice up the tomato (I usually use a quarter of it) and cut the slices into quarters for easier eating (I hate when the whole slice comes off the sandwich when you're trying to eat it). Squeeze on some lemon juice (make sure to squeeze a little on the remaining avocado before storing to prevent browning), and salt if you'd like.
Top with the other slice of bread. Cut in half and enjoy!
This sandwich is also good with cucumber and lettuce or sprouts.