Preheat oven to 400 degrees. In a large bowl, sift together the dry ingredients. Finely chop the butter. By hand or in a food processor, blend with the dry ingredients. The mixture should not be thoroughly blended, but should have small, pea-sized clumps of butter and flour. In a small bowl, whisk the eggs and buttermilk together. Stir in the sun-dried tomatoes and thyme. Work together the dry and moist ingredients until the dough begins to come together. Do not overwork or your biscuits will be tough. Turn the dough onto a floured board and roll into 1/2-inch thickness. Fold in half and roll out again. Fold in half one more time and roll into 3/4-inch thickness. Cut the dough into 2-inch square biscuits. Bake on a lightly oiled baking sheet for about 12 minutes or until the biscuits are fluffy and browned.