To cook eggs: In a small pot, add eggs and cover with water. Bring to a boil, turn down to simmer, and cook for 20 minutes. Drain water and place eggs in a bowl of ice water for several minutes. When chilled, peel eggs.
In a small bowl, using a cheese grater, shred 2 whole eggs and 2 whites. Throw away the other 2 yolks or use them in another recipe. Stir in mayonnaise, relish, mustard, curry powder, salt and pepper, to taste.
Split open sandwich thins and spread mustard inside of each piece. Divide egg salad among 2 pieces. Top each with tomato, spinach, and remaining sandwich thin.
You can heat the sandwich in the microwave before adding the tomato and spinach. It tastes really good warmed.