The problem with the question about what will increase nutrition is that it is a question asked out of ignorance.

Whatever you add will add nutrition.
You can add sugar and you will techincally get more nutrition.

The question you should ask yourself is what nutrition you want.

People have this strange notion that nutrition is a meassure of how healthy something is, which is a misconception.

Nutrition is what you eat that the body needs, this includes macronutrients (such as carbs, protein and fat) and micronutrients (such as vitamins(which is a misnomer and not a very good term), minerals and such)

Now to understand what would make that recepy more healthy you need some basic knowledge about nutritional science.

A simple calculation fo your ingrident list give me that this this whole stew is worth more than 12MJ or almost 3 Megacalories or 3000 kilocalories or 3000000 calories. I've heard that americans tend to think that kilocalories are calories so just look at the kilocalories if you're american. That is more than the average joe needs in a day, but then again this is probably a 4 person serving which makes sense.

Now more interestingly how much of that energy is what sort of nutrition?
Makronutrition comes in 3 forms (4 with aclhohol but let's not get into that now)
We need all three of them and in general it's a good idea to meassure how much of them we need in percentage of energy they will give you.

Your dish gives you:

* approximately 361g of carbohydrates, which is ~6MJ
* approximately 56g of fat which will give you ~2MJ
* approximately 242g of protein which would amount to ~4MJ

which gives you the following energy percentages: 

* carbs: ~50%
* fat: ~17%
* protein: ~33%

Which is good, perhaps a bit low on fat.

Now, it's not that easy really, what sort of carbs, fat and protein you take also matters, carbs comes in many forms (eating a lot of suger is going to give you lots of glucose fast which is not a good thing, while spagetthi will give you a somewhat slower and more even glucose intake), fat is divided into what sort of fatty acids it's built of (i'm not going into detail but oversimplified you need them all but not as much of each) and finaly protein is built out of amino acids which the body uses to build various things (9 of these are essential for an adult human and we need them in different amounts). I'm not going to analyse to this detail here but you should know it's not as simple as only energy percentage.

When it comes to micornutrients i'm not going into too much detail, no single meal is going to be perfect in the sense of all micronutrients anyways, the more important thing is that you eat a variety of different foods and you most likely be covered, but if you want to make sure i suggest you write down evertyhing you eat for 2 weeks and make an analysis on that or just go to a professional. I will add that it is a bit high on sodium though, a lot of food is.

I hope this helps. Remeber kids: stay informed.

EDIT: fixed the lists and also added note about the complexity of macronutrients.