Place kumara in a steaming basket over a small saucepan of boiling water and steam for 8 to 10 minutes or until just tender and then remove from heat and cool (I would use my electric steamer).
Make Satay sauce - Heat oil in a small saucepan over moderate heat and add onion and garlic and cook and stir for 1 minute or until fragrant and then add remaining ingredients and cook and stir until smooth and heated through.
Thread tofu, corn and kumara onto 6 skewers, alternating ingredients.
Combine 1 tablespoon of the oil and soy sauce in a small bowl and brush skewers with soy mixture.
Preheat a barbecue or char grill to moderately high and cook skewers for 10 minutes or until browned.
Combine cabbage, cucumber and tomato in a medium bowl and drizzle with juice and remaining oil.
Place in a serving owl and top with egg and drizzle skewers with satay sauce and sprinkle with onion and serve with salad.
NOTE - if using wooden skewers soak for 30 minutes in water before using.