Line a serving platter with the fresh baby spinach leaves; arrange slices of tomato around edge of spinach; sprinkle salt and pepper and chopped green onion around tomato slices. Set aside.
Heat oil in a medium frypan, saute onion until soft, about 5 minutes. Add tomato, spinach, capers and ricotta cheese, cook, stirring 1 minute or until heated through. Remove from heat, season with salt and pepper, set aside to cool. Do not rinse the frypan, it will be used to poach the roll.
Squeeze lemon over fillet and sprinkle with the dill. Spread the filling evenly over the fillet. Starting at the tail end, (shortest end), roll fillet up like a jelly roll. If necessary use toothpicks to hold.
Add the milk to the frypan, bring to simmer and deglaze. Carefully add the filled sole roll to the milk, seam side down, spoon milk over the roll; cover and simmer/poach for about 10 minutes, or until fish flakes and is cooked through. Sprinkle with parmesan shreds and carefully remove to the centre of the arranged platter; cut the roll evenly in two; drizzle a little of the reduced milk over platter arrangement and fish; sprinkle with green onion; serve immediately.