Preheat the oven to 180°C/350°F/Gas mark 4
Peel and mash the bananas. Cream together the oil, bananas, and sugar. Mix the flour with sunflower seeds and soda. Add dry ingredients to banana mixture and stir until thoroughly mixed.
Drop dough by rounded tablespoonfuls about 2" apart onto ungreased cookie sheet. Bake about 15 minutes, until edges are golden brown.