Dissolve Yeast In 1/2 Cup Warm Water. Stir In 2 Cups Of Lukewarm Water, Flour, Salt And Sugar. Beat Until Smooth. Let Stand, Uncovered For 3 To 5 Days, At Room Temperature. Stir Two Or Three Times A Day. Cover At Night. When Ready, The Mixture Should Smell Yeasty But Not Sour. Pour Out 1 Cup Of Starter To Use In The "Friendship Mixture". To Keep This Starter, To The Leftover Starter, Add 1/2 Cup Water, 1/2 Cup Flour And 1 Teaspoon Sugar. Let Stand For At Least One Day, Until Bubbly And Well Fermented. Store In Refrigerator, Covered, For Up To Ten Days. Use Within 10 Days To Make Another Friendship Mixture.