You can cook the veggies in open pan but it takes time to finish.
Your choice of veggies may vary but yellow pumpkin and avarakkai is a must.
In stead of sweet potato you can use regular potato or even yam.
Add tamarind according to the tanginess and taste.
You can add little ghee at the end but its optional.
I have cooked both field beans and dal together but you can boil it separately.