user: Question: What was the surface when the opponent was Judith Wiesner, and the outcome was Winner?
Columns: ['Outcome', 'Date', 'Tournament', 'Surface', 'Opponent', 'Score']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Winner', '23 April 1984', 'Taranto', 'Clay', 'Sabrina Goleš', '6–3, 7–5']
SQL:

assistant: SELECT "Surface" FROM "Table" WHERE "Outcome" = 'Winner' AND "Opponent" = 'Judith Wiesner';