To a small bowl, mix together the one tablespoon olive oil and red pepper flakes. Allow to sit for 15 minutes. Run the oil through a sieve, discarding the red pepper flakes. (Alternatively, you could do as I did and just scoop out some of the oil, trying your hardest to avoid the pepper flakes.)
Place a cast iron skillet over moderately high heat. Pour about two tablespoons of olive oil and when the oil is near the smoking point, add the beans, allowing them to cook on their first side for 2-3 minutes. When the skins are blistered, flip the beans, cooking on their opposite side for an additional 2 to 3 minutes. Remove and transfer to a bed of paper towels to drain.
To a medium bowl, add the green beans. Pour in the chili oil (to taste), the mint leaves and a pinch of salt. Toss until thoroughly coated. Transfer to a serving plate and garnish with zest from 1/2 small orange. Serve immediately.