A Work in Progress-Latest Spaghetti & Meatball Recipe

I love spaghetti and meatballs, but am still playing around with different combinations to find the version I like the best.  Here's my latest version...I welcome your tips and insights on preparing this simple meal with so many variations! 

For the meatballs, I largely followed this Food Network recipe for Albondigas.  They were tasty served as an appetizer, and I also liked that they don't use eggs to bind them together (my son is allergic).

For the Meatballs:
1/2 large onion, chopped fine
1/2 large green bell pepper, chopped fine 
about 5 tablespoons olive oil
1 pound ground beef (not lean)
1/4 pound ground pork (not lean) 
1/3 cup fine dry bread crumbs (I substituted ground flax seed)
1 tsp salt
1/4 teaspoon fennel seed
1/8 cup minced fresh parsley leaves

For the Sauce:

1/2 large onion, chopped fine
4 medium garlic cloves, minced
36 ozs canned tomatoes (San Marzano ideally--I used Pastene brand with basil because it was on sale; I usually would add my own basil)
1 tbsp balsamic vinegar; 2 tbsp olive oil
3 tsps mixed herbs--I used parsley, oregano and rosemary

salt & white pepper to taste
tsp of ground flax seed to thicken--I'd usually use a tbsp of tomato paste but didn't have any on hand

Make the Meatballs:  In a 9-inch heavy well-seasoned skillet (preferably cast-iron) cook onion and bell pepper in 2 tablespoons oil over moderately low heat, stirring occasionally, until softened. Cool mixture. In a large bowl combine well onion mixture, ground meat, bread crumbs, salt, nutmeg, and parsley. Form level tablespoons of mixture into balls.  In skillet heat 1 tablespoon oil over moderately high heat until hot but not smoking and brown meatballs in batches, shaking skillet frequently so that meatballs maintain their shape and adding remaining 3 tablespoons oil as necessary. Transfer meatballs with a slotted spoon as browned to a bowl.  I'm learning getting the meatballs good and browned helps keep them together when they cook in the sauce.

Make the Sauce:  Heat the olive oil in a large, heavy pan.  Saute onions over medium heat until soft, about 5 minutes.  Add garlic, saute another 2 minutes.  Add the tomatoes, breaking up the tomatoes as you stir them in.  Bring to a simmer and add the meatballs to the sauce.  Stir in the remaining ingredients, and simmer for at least an hour.  Serve over spaghetti or linguine.

Wine Pairing:  This one's easy!  Chianti is the natural choice for spaghetti, with enough acidity to match the tomatoes.  I had a good bargain recommended to me at the wine shop, the 2006 Strozzi Chianti ($10).  Seeing it was young, I let it breathe for a solid hour, after which it showed soft, lush plummy fruit and just a bit of leatheriness to give it some backbone.  If you find this one in the store, pick up a few bottles for simply pasta or pizza meals!