Preheat oven to 300° F. Thinly slice or julienne the carrots and celery. Dice the green onions very finely. In a medium non-stick frying pan, melt the butter over medium heat and lightly sauté the vegetables for five minutes, or until soft. Season with sea salt and freshly ground black pepper to taste. Set aside and cover to keep warm. Use a food processor and blend the yogurt, Worcestershire sauce, walnuts and lemon juice. Add the maple syrup or honey and garlic. Process these ingredients until they are blended and become a smooth paste with a slightly runny consistency. Remove the pits from the avocados and peel them. Slice each avocado into quarters (you will end up with 4 four slices cut lengthwise with each avocado). Brush all sides with lemon juice to prevent browning. Place on a tray lined with parchment paper and bake in pre-heated oven for about 8 to 10 minutes. While the avocado is baking, heat the tomato sauce. Meanwhile, heat two plates so they are warm. Spoon the warm, cooked carrots, celery and green onion mixture evenly into the centre of each plate, spreading them around to form a circle about 10 cm in diameter. Drizzle with some of the creamy yogurt sauce. Top with some of the fresh basil. Place a slice of avocado on each bunch of mixed vegetables and spoon about a teaspoon of the yogurt sauce over them. Repeat with remaining avocado slices until each plate has 4 slices stacked on them. Top each plate with some warm tomato sauce and drizzle remaining yogurt sauce over the tomato sauce. Garnish with a sprig of fresh basil and serve warm. Makes 2 servings.
