For the chicken salad:
1. In a large saucepan combine the wine, salt, peppercorns, lemon juice and thyme. Add the chicken breasts and enough water to cover them. Bring the liquid to a boil, reduce the heat and simmer for 10 minutes. Remove from heat and let the chicken cool in the liquid.
2. To make the curried sour cream, heat the oil in a small saucepan over medium-low heat. Add the onion and cook until the onion is very soft, about 5 minutes. Add the curry powder and cook for 2 more minutes. Remove from heat and cool. Stir in the sour cream.
3. When the chicken is cool enough to handle, remove it from the liquid. (Discard the liquid.) Cut the chicken into small pieces, place it in a bowl and toss it with the curried sour cream, grapes and almonds. Season to taste with salt and pepper. Refrigerate until ready to serve.
For the sandwiches:
4. Place 4 pieces of bread on a work surface and place a leaf of lettuce on each. Spoon the chicken salad on top of the lettuce leaves and top each sandwich with another piece of bread. Serve.