Heat oven to 400 degrees F. Line the pan with muffin liners.
In large bowl, whisk together flour, baking powder, and salt. In medium-size bowl, whisk eggs, milk, juice, sugar, oil and zest, sour cream, vinegar, and ricotta. Make a well in flour mixture; pour in egg mixture and chocolate chips. Stir until dry ingredients are just moistened (although, be sure to not over-mix for it will result in overly-tough muffins).
Spoon approximately 1/4 cup batter into each muffin cup. Bake in a 350 degree oven for 18-20 minutes or until toothpick comes out clean.
Remove pans to wire rack to cool 5 minutes. Serve.