Bring the butter to room temperature to soften. Squeeze the lemon.
Rinse and drain the basil, parsley, garlic, onion. Put them into a food processor. Add the lemon juice, salt and pepper and blend into a paste.
Add the basil paste into the softened butter and mix everything together.
Season with salt. Transfer into a container lined with a sheet of plastic wrap. Chill in the fridge to harden.
After the butter has hardened, cut into manageable sizes.
Here 's a beef steak that uses this butter. (Recipe ID: 1060457)
Story Behind this Recipe
Every year, I used to eyeball the ingredients to make this butter, but I ended up with this recipe now. Maybe the authentic kind doesn't use lemon juice or butter, but I use them anyway because my family likes it.
I make this butter in bulk whenever I harvest the basil in my home garden. I usually freeze it in an airtight container. I use this for cooking for a whole year until when I'm able to harvest my basil again.