Trim the green beans. Fill a large bowl with ice water and set to the side.
Fill a large pot with water and bring to a boil. Salt generously, then add the green beans and set a timer for 3 minutes.
When the timer goes, immediately drain the beans and plunge into the ice water to stop the cooking.
Once the beans are cool, drain in a colander and then pat dry with a clean dish towel.
Make the gremolata. In a small bowl combine lemon zest, parsley, garlic, parmesan, and toasted sunflower seeds. Season with salt and pepper.
Heat the olive oil in a large, wide frying pan over medium-high heat.
Add the blanched green beans, and sauté for about 5 minutes, stirring frequently, until the beans are warmed through.
Remove from the heat, add the gremolata, and toss to coat the beans well.
Transfer to a serving dish, and serve immediately, at room temperature, or cold.