Preheat oven to 275ºF.
Heat 1 tablespoon extra virgin olive oil over medium heat in a wide, ovenproof pot. Add the onion and cook, stirring occasionally, for 5–7 minutes until translucent. Add salt and pepper.
Add the cherry tomatoes and season with salt, pepper, and a big pinch of crushed red pepper. Cook for 8–10 minutes until the skins split, mashing a few tomatoes into the onions. Season with salt and pepper.
Add the olives and 1 cup water. Bring to a boil, then turn off the heat. Taste and season.