Preheat oven to 375 F. Slice baguette into ~1/2-inch thick pieces. Brush both sides with olive oil and spread on a large baking sheet. Bake for a total of 10 minutes, flipping halfway (5 mins each side) until slightly toasted. Remove and let cool.
Meanwhile, make beet creme fraiche spread by adding all ingredients (except the canned salmon) to a food processor. Blend until smooth. Season to taste and set aside.
Next, make the mashed avocado spread by adding the canned salmon, avocado, and lemon to a bowl and mashing with a fork until well combined. Salt to taste.
Thinly slice the cucumber, using a mandolin if you have one. Chiffonade the basil, and prepare the dill sprigs.
Once all ingredients are ready, it's time to create the crostini! You will have approximately 8 of each "flavour." Spread beet creme fraiche over 8 pieces of bread, then add a spoonful of canned salmon to the top, finishing with a sprig of fresh dill.
Next, spoon some of the avocado mash over 8 pieces of bread, then add basil and a drizzle of balsamic vinegar over top.
Finally, spread remaining bread pieces with cream cheese, top with 3 cucumber slices on each piece, then spoon canned salmon and top with a sprig of fresh dill. Crack black pepper over top of all crostini, and then serve immediately!