Here is a little gem, fell out of my cookbook (guess he figured his time was ripe).  It is like a Friendship Bread in that one is given Siegfried sourdough sample and a recipe with instructions.  I think it's funny how it contains both metric and cups.  I would just take a sample of your own sourdough and try it.  How much?  Anywhere from a tablespoon  to 1/2 cup, up to you....  Thoughts & comments welcome.

1. Day One:  Feed Siegfried with 1 cup Milk, 1/2 cup Powder Sugar, 1/2 cup Flour
2. Days Two through Four: Stir
3. with lots
4. of tender loving care.
5. Day Five:  Feed like Day One
6. Days Six through Nine:  Stir
7. with lots
8. of tender
9. loving care.
10. Day Ten:  Divide Siegfried into 3 parts.  Save one part, give one away, and useone part in the following recipe:

IMPORTANT: No Refrigerator,  No Metal, Loosely cover Dough

Rye Bread Dough:

• 1 part Siegfried
• 500g wheat flour
• 500g rye flour
• 2 pkg dry yeast (1pkg enough to lift 500g flour)
• 10g -15g salt
• 40g Breadspice
• 3 cups to 4 cups (with a note,"4, a little too much") warm water
• note added: Sunflower seeds, pumpkin seeds, or walnuts   

Work all ingredients into a smoothe dough and let rest in plastic bowl in a warm place for 2 hours.  Eventually form the bread and spray with water.  Bake on baking parchment 200°c for 1 hour  or 175°c with convection.  Spray several times during the baking with water (with note:" once is enough")