You can prepare the quiche crust several days ahead: Make the dough, transfer it to your tart pan and freeze it, tightly wrapped in plastic, until you’re ready to blind bake it.
Make the terrine, bake the salmon for the dip, and make the lemon olive oil the night before brunch to further streamline your prep.
To serve a crowd, mix up a big batch of the cocktail ahead of time. Then simply shake individual portions to chill before serving. For a non-alcoholic treat, combine the lemon juice and chamomile-honey syrup with a little soda water.