Cut chicken thighs into 1 1/2-inch pieces and thread on skewers. Put a piece of green onion between chicken chunks. Salt and pepper skewered chicken. Grill until slightly golden brown. Sauce each skewer and continue grilling until the sauce caramelizes, about 3 minutes.
For Sauce: Cook all ingredients over low heat until the consistency of syrup. For a thicker sauce, dissolve some corn starch in cold water and add little by little to ingredients once they are heated up.