Combine cider, lemon juice and tarragon, and marinate liver in mixture for 1 hour.
Dust liver with salt and yeast.
Cut onions, peppers and tomatoes into wedges, chunks or slices convenient for skewering, depending on their size.
If mushrooms are small enough, leave these whole.
Alternate liver on skewers with vegetables and mushrooms.
Brush lightly with oil and broil briefly, turning skewers several times to brown liver uniformly.