"A quick, low-meat, low-cost yet delicious meal. I came up with this while living in Japan where meat is very expensive. This is a very forgiving recipe and I've made many substitutions over the years, such as garlic instead of onion, cabbage instead of napa, and even made omissions when low on ingredients and every time it turns out fine."
Put bacon and onion in a large covered skillet over medium-high heat; cook and stir until onions are translucent and bacon is still soft, about 5 minutes.
Cut each package of udon into quarters; add to the skillet. Cook and stir until noodles absorb bacon grease and fall away from each other, about 5 minutes.
Stir broccoli and napa cabbage into the skillet; sprinkle sesame seeds and black pepper on top. Cover the skillet and reduce heat to medium; cook, scraping and folding with a wooden spatula a few times, until tender, 5 to 7 minutes.