In a large saucepan melt the butter with the oil. Add the chopped onions, garlic, and pearl onions. Cook and stir over low heat until golden, about 15 minutes. Do not brown. Combine the tomatoes, sugar, honey, wine, vinegar, lemon juice, water, currants, fennel, and cayenne pepper. Stir into the onion mixture. Simmer, covered, over low heat until the onions are tender. Stir frequently. Uncover and cook until thick and syrupy, stirring constantly to avoid scorching. Add the corn. Cook and stir 15 minutes longer. Cool. Spoon into clean, half pint glass containers with tight fitting lids. Refrigerate. Bring to room temperature before serving.