In a large, low side pan add the butter and oil and cook the onions, celery, carrots and parsley until tender. Add the wine, the chicken stock, cover, lower the heat to medium low and cook for 5 minutes.
Add the tomatoes and cook for another 15 minutes over medium high heat.
Dry the swordfish fillets and spread some light butter over the top and season with salt and pepper.
Place the swordfish over the tomatoes sauce and cook over medium high heat covered for another 5 to 8 minutes.