Place a slice of lemon on each breast and season with the pepper. Line a tray with foil and grill chicken (b.b.q. works well also) until chicken is tender and serve the chicken with the sour cherry sauce.
*Drain the pitted black cherries and reserve the juice.
Place vinegar and sugar in a saucepan, bring to boil, and cook stirring constantly until mixture caramelizes.
Blend the cornflour with 2 tablespoons of cherry liquid, and put the left over juice into the saucepan with the stock, rinds juices, cherries and liquid, cook another 3 minutes.
Add cornflour paste stirring until combined (with no lumps) and thickened.