Cut off the stems of the bell peppers and remove the seeds. Mince the onion.

Place the minced onion in a microwave-safe container, cover loosely with plastic wrap, and microwave at 600W for 1 minute. Let it cool.

In a plastic bag, mix breadcrumbs and milk until combined. Add ground pork, microwaved onion, and remaining seasonings. Knead until the mixture becomes sticky.

Cut off the tip of the plastic bag and squeeze the meat mixture evenly into the bell peppers.

Heat olive oil in a frying pan over medium heat. Place the stuffed peppers meat-side down and cook until browned.

Add diced tomatoes, water, salt, and pepper to the pan. Stir and bring to a boil. Cover and simmer on low heat for 10 minutes.