Saute 1/4 c. chopped onion and 1 clove minced garlic in 1 tsp. sesame oil until softened. Add 2 tbsp. lemon grass, 1 tsp. Oriental chili paste, 2 tsp. soy sauce, 2 tsp. freshly grated ginger, 1/2 tsp. each ground cumin and coriander. Cook for 2 minutes. Stir in 1/4 cup tahini and heat until melted. Remove from the heat and stir in 1 cup yogurt. Grill 4 lightly pounded chicken breasts 4 inches away from a high flame until firm. Slice the grilled chicken thinly and toss with the tahini sauce. Serve over chilled cooked celluphane noodles.