Apple Streusel Muffins

2 cups flour
1 cup sugar
1 Tbsp. baking powder
1 1/4 tsp. cinnamon
1/2 tsp. salt
1/2 tsp. baking soda
2 eggs
1 cup sour cream or (milk with 1 tsp. vinegar added, let stand 5 minutes).
1/4 cup oil
1 cup finely chopped apple

Topping:
1/4 cup sugar
3 Tbsp. flour
1/4 tsp. cinnamon
2 Tbsp. butter (soft)

In a large bowl, combine eggs, sour cream and oil. Add all at once to dry ingredients. Add apple. Put in muffin tins 2/3 full. Sprinkle on topping. Bake at 400 F 20-25 minutes.