preheat oven to 450
mix up all the ingredients in a bowl and stir the chopped turnips and kohlrabi around in there - i'm not sure a longer marination time would be helpful, but you could try!
line a baking sheet or pan (with edges) with parchment paper or equivalent
pour bowl with turnips and kohlrabi and all liquid onto parchment paper - depending on your preferences, there may or may not be a fair amount of liquid that they are sitting on. i like to bake things with this liquid because sometimes it adds a nice crispy vibe and kind of steams them as they bake as well. but follow your heart!
bake at 450 for 30-40 minutes, or until browned and crispy on the outside, and soft on the inside. you should be able to easily push a fork through.
get out the ole food processor or blender or submersion blender or mortar and pestle
depending on your method, pre-chop turnip tops, green onion tops, and scapes as fine as possible or as rough as you like.
(if you're adding seeds to make a pesto, grind those up fine separately if you are going manual on this one)
toss them all into whatever you are using to macerate them
add lemon juice and olive oil to taste and to the texture you prefer
add salt and pepper to season afterwards if you wish!