Mix self-rising flour and greek yogurt together in a medium bowl until well combined. Knead for 60 seconds on a lightly floured surface until a ball is formed.
Roll dough out so it will fit comfortably in a greased 9x13 glass pan. Make perforations in the dough to create 20 rolls that can be pulled apart easily. Brush rolls with the egg wash and sprinkle evenly with poppy seeds, onion, and sea salt.
Bake for 22-24 minutes. Remove from oven and prick each roll with a fork. Drizzle butter evenly over the rolls and bake for an additional 6 minutes, or until golden brown.
While pull-apart rolls are baking, whip softened butter until fluffy and almost doubled in size with a hand mixer or in a stand mixer. Be sure to scrape butter down off the sides of the bowl.
Add Dei Fratelli Seasoned Diced Tomatoes, reserved juice, banana pepper, vinegar, salt, and black pepper. Mix for an additional 30 seconds on high. Serve with rolls.