Start by scooping out the avocado flesh into a mixing bowl.
Add chickpeas to the same bowl.
Using a fork or masher, gently mash the chickpeas and avocado together until it reaches a slightly chunky consistency.
Sprinkle in salt, black pepper, and then drizzle lemon juice over the mix.
Mix in chopped cilantro (coriander) to this mashed mix.
Now, take your whole wheat bread slices and lightly brush them with olive oil on one side.
On the opposite side, spread the mashed avocado and chickpea mixture generously.
Place thinly sliced tomatoes and a lettuce leaf on two slices.
Close with the remaining slices, with the oil-brushed side facing out.
Heat a skillet or sandwich maker.
Once hot, place the sandwiches and grill until they are golden brown on both sides, typically about 2-3 minutes per side.