Heat the oven to 355°F (180°C).
Line a baking sheet with parchment paper. Spread the sweet potato cubes on the sheet and drizzle with olive oil. Sprinkle with oregano, chili flakes, cumin, salt, and pepper, and toss to coat evenly.
Roast the sweet potatoes for 30 to 35 minutes, until very tender and caramelized at the edges. Set aside to cool slightly.
In a food processor, combine the roasted sweet potatoes, chickpeas, olive oil, tahini, garlic, lemon juice, and 1/4 cup cold water. Blend until smooth and creamy, scraping down the sides as needed. Add more water, a tablespoon at a time, until the mixture reaches your desired consistency. Taste and adjust seasoning.
Transfer the hummus to a shallow serving bowl and use the back of a spoon to create swirls. Top with reserved chickpeas, sesame seeds, chili flakes, and cilantro. Drizzle with olive oil and serve with warm pita bread or crisp vegetables.