Clean the chicken and place in a gallon size ziploc or a food container big enough to hold the chicken. Combine the lemon juice and soy sauce and pour over the chicken. Let sit in the refrigerator for at least 4 hours or overnight. Turn chicken halfway to marinate evenly.
Preheat the oven to 425 F.
Drain and discard the marinade. Place the lemongrass and garlic inside the chicken cavity. Tuck the chicken wings under the body and tie the legs together with a kitchen twine. Brush the outside of the chicken with a little olive oil ( abt 1 tbsp ).
Put potatoes and onions in a roasting pan. Drizzle with olive oil and a sprinkle of salt and pepper. Arrange the vegetables in the middle of the pan and position the chicken on top of the vegetables.
Drizzle the eggplants with olive oil and season with salt and pepper. Set aside and add after the first 30 minutes of cooking time so it won’t overcook.
Roast for 1 hr 15 minutes to 1.5 until the juices run clear when you stick a knife in the inner part of the thigh. Remember to add the eggplants.
Cover loosely with foil for 10 minutes before serving.