In a large heavy-based pan, melt the butter and 1 tablespoon oil over a medium heat until foaming. Add the onions and mix well. Cover and cook gently for 10 minutes, stirring occasionally. Add the caster sugar, increase the heat and cook for a further 10-15 minutes, stirring frequently, until golden
Meanwhile, heat remaining oil in a large frying pan, then add the sausages and cook over a medium heat for 12-15 minutes, turning frequently, until cooked. Turn down the heat
Mix together the honey, soy and Tabasco sauces and pour over the sausages. Stir until glazed
Pop a sausage into each roll and top with caramelised onions