In a large sauté pan, melt the coconut oil over medium heat. Add the anchovies and red pepper flakes, stirring occasionally, until the anchovies melt into the oil - about 2 minutes.
Toss in the garlic and sauté for another minute until fragrant.
Stir in the tomato paste and cook for 1 minute, then add the chopped tomatoes. Stir well and cook for another minute.
Add the parsley, capers, and black pepper, mixing everything together.
Add the celery to the pan, stirring to coat it thoroughly in the sauce. Lower the heat to medium-low and braise for 20 minutes until the celery is tender and infused with all the saucy goodness.
Serve hot - and if you like an extra kick, sprinkle on a bit more red pepper flakes.