Soak sweetbreads in cold water for at least four hours, or up to overnight, changing the water three to four times.

Place sweetbreads in a medium pot, cover with cold water, and add lemon juice and a teaspoon of salt. Bring to a boil and cook for five minutes. Remove sweetbreads immediately and place in an ice bath.

Once cool, place sweetbreads on a few paper towels and dry very well. Remove all the membranes and veins. Place in refrigerator overnight.

Heat oil in a large frying pan. Season sweetbreads with salt and pepper and add to heated pan. Fry until golden brown on one side, then turn over and fry on the second side. Remove from pan.

Add sliced onions to the frying pan. Sauté until they start to wilt, then add mushrooms and peppers.

Stir wine and potato starch into chicken broth. When the vegetables start to soften, add the wine mixture to the pan. Season with salt and pepper and set aside.

Prepare gnocchi according to package instructions. Toss gnocchi with vegetable mixture.

Spoon vegetables and gnocchi in the center of each plate and top with fried sweetbreads.