Top and tail the pimentos, cut in half, remove the pith and seeds, and cut into thinnish strips. Peel the ginger and cut into thin slices. Peel the garlic cloves and crush. Cut the chillis lengthwise, remove seeds and cut into small pieces. Add the pimentos, ginger, chillis and garlic to a blender and blend.
Put the tomatoes into boiling water, take out, peel, cut into quarters discarding the seeds. Put a tablespoonful of olive oil into a thick bottomed saucepan, add the tomatoes and pimento mixture and simmer for 30 minutes mashing from time to time.
Season the relish with salt, some black pepper and if needed a little sugar. Put to one side and re-warm when required.