How to make vegetarian meat substitute that's more firm and browned on the outside?
In my experience, you will not get TVP nuggets by themselves to ever have a chewy, crispy, or meaty texture.  However, there are some other products you can use that allow you to have better texture.
One thing you can do is to mix rehydrated TVP with wheat gluten, and then knead it to develop texture.  Wheat gluten is the chewy part of bread, and when kneaded develops into long, tough strands, adding chew and texture to your meat substitute.  Many of the &quot;vegetarian meat&quot; items that you find in Asian grocery stores are primarily wheat gluten.  The ultimate form of of fermented and kneaded wheat gluten is seitan, and you can also buy this directly to make things from it.
The other product that has been very popular for a better texture is soy curls.  These are a soy protein product that has been processed differently, and they have a much denser texture than TVP.  They also fry up nicely, browning a lot better than TVP or tofu does.
My own experiments with making fake breakfast sausage show that a combination of products is generally necessary for best texture.  Currently I'm using TVP, wheat gluten, and dried and rehydrated mushrooms.  I may experiment with adding oats soon.  Good luck with your vegetarian experiments.