Cut avocados lengthwise, around the pit. Twist each half in separate directions, to pull apart. Holding the half with the pit in one hand, whack the pit with a large sharp knife. Twist it until the pit pops out. Do so for each avo.
Cut the halves into slices with a spoon and then scoop out the fruit into a mixing bowl. Mash with a potato masher.
Add lemon juice and salt and mix well.
Toast the bread slices. Using a large knife, cut the bread into triangles.
Spread the avocado onto a triangle and build out a tree. One triangle at the top, two on the next row, three on the following but close together, and three on the bottom but spread apart.
Trim the crust from the remaining toast to make the trunk of the tree. Use a star-shaped cookie cutter, or just a knife, and carve out the star from a remaining piece of toast.
Slice the cherry tomatoes and use the slices as ornaments on the tree.
Serve immediately. Enjoy!