In a medium saucepan, bring water and a pinch of salt to a rolling boil. Add kasha and boil for 10 minutes. Remove from heat, pour through a strainer, and rinse with cold water.
Combine the cooked kasha in a bowl with fennel, apple, shallot, and parsley.
In a separate bowl, whisk together vinegar, mustard, salt, pepper, and olive oil.
Pour dressing over kasha mixture and stir until evenly combined.
Serve this salad as a side and top with crumbled feta cheese.