Heat the oil in a large skillet over medium heat. Add the onion, garlic, thyme, and rosemary. Cook until onions are translucent, 5 to 6 minutes. Add beans with their liquid, 1 cup of water, salt, pepper, and cayenne, and bring to a simmer. Cook until liquid is nearly evaporated, about 8 to 10 minutes. Remove thyme and rosemary sprigs; discard. Carefully transfer mixture to the bowl of a food processor, add the tahini and lemon, and puree until smooth. Adjust seasoning, if necessary. Transfer to a serving bowl, let cool.
Top with Kalamata relish and drizzle with olive oil before serving. Serve with pita triangles.