converting yeast recipe to sourdough

I have this wonderful recipe that I've made many times.  I'd be interested in how I might convert this to a recipe using a starter instead of yeast>

BE honest - am I better off leaving well enough alone since I do LOVE this recipe?

-Susie

Coarse Salt and Rosemary Focaccia Bread

2 tsp Active Dry yeast
2 cup Warm Water
8 TB Olive Oil
5 C. Unbleached flour (can use bread flour or whatever you have)
1 TB Salt
3 TB Fresh Rosemary Leaves (I have been using dry)
1 TB Coarse Salt (Kosher Salt)

Combine yeast and warm water in bowl.
Add 3 TB olive oil to the water and let soak for 5 minutes

Mix the flour, 1 TB salt and 1/2 the Rosemary together.
Add the yeast water mixture to the flour. Stir with wooden spoon til mixed.

Turn onto floured surface and knead for about 10 minutes.

Place into lightly oiled bowl and let rise til double.

Punch down dough and spread onto lightly oiled jelly roll pan or cookie sheet.
Let rise again til doubled.
(You can also shape individual bun size (3" diam) portions and place on sheet to rise).

Before baking, punch indentations in top of dough with your fingers. Drizzle with
remaining Olive oil and sprinkle with the Coarse salt and remaining
Rosemary leaves. (I don't always use ALL of the oil and salt)

Bake at 450 for 20 minutes or until golden brown.

This recipe is fantastic when lightly toasted and served with
grilled chicken breast smothered in sauteed mushrooms and
onions and served with honey mustard sauce.