Frittata with asparagus, mastiha and herbs

Preheat the grill with the rack about 20 cm below the heating element.
Bring a large pot of salted water to a boil and blanch the asparagus for 1-2 minutes. Drain and immediately immerse them in a bowl of ice water to cool down. Drain them again and cut the asparagus into 5 cm pieces.
Grind the mastic with a pinch of salt. In a large bowl, whisk the eggs with the mastic-salt mixture, a bit of pepper, and the grated graviera or parmesan.
Heat the olive oil in a large cast-iron pan over high heat, add the onion and garlic, and sauté for 2-3 minutes.
Add the asparagus and cook for 1 minute, stirring gently. Add the tomatoes and herbs, and stir lightly. Pour in the eggs and shake the pan to cover the surface evenly. Lower the heat and cook the frittata until the bottom is set, about 6-8 minutes.
Transfer the frittata to the grill and cook for another 6-8 minutes until the top is golden brown. Cut into triangular pieces and serve, either warm or at room temperature.