Mini flank steak skewers with Asian grapefruit sauce

Ingredients

• 1 kg plain flank steak, cut into short strips against the grain
• The juice of 2 fresh grapefruits
• 3 large garlic cloves, finely chopped
• 1 green onion, thinly sliced ​​+ a little for serving
• 3 tablespoons soy sauce
• 3 tablespoons honey
• 2 tablespoons olive oil
• 2 tablespoons hoisin sauce
• 2 tablespoons sesame seeds
• 1 tablespoon sesame oil
• 1 tablespoon grated fresh ginger
• Salt and pepper from the mill