Irish Lassie s Liver and Onions

1 teaspoon olive oil, or more if needed

1 clove garlic, minced

4 large sweet onions (such as Vidalia®), thinly sliced

1 ½ tablespoons finely chopped green bell pepper

1 ½ tablespoons finely chopped red bell pepper

½ cup sliced fresh mushrooms

salt and black pepper to taste

¼ cup butter

1 pound calf s liver, skinned, deveined, and sliced

¼ cup all-purpose flour

2 cups cold water

2 teaspoons beef bouillon granules

1 tablespoon red wine

Heat the olive oil in a large skillet over medium heat. Stir in the garlic, onion, green bell pepper, red bell pepper, and mushrooms; cook and stir until the onion has softened and turned translucent, about 5 minutes. Season with salt and pepper. Push onion mixture to the side of the skillet, and place the butter in the center of the skillet. Add calf s liver, one slice at a time. Cover and cook until lightly browned, flipping liver slices once, 5 to 6 minutes. Cut liver slices in half.

Whisk together flour, water, and beef bouillon in a bowl until combined. Pour mixture into the skillet; cook and stir until gravy thickens, then add red wine. Cook for 2 more minutes. Remove from heat and serve.