Hi JohnSmith4,
that recipe is traditional rather than restaurant or takeaway, in that its base is tomato rather than an onion gravy(base), which gives a sweet background against the spices which can be bitter.
Traditional 'Indian' cookbooks are full of recipes like that one. Coconut being another base in Southern Indian cuisine.
Some places would mix the different spices(mix powder) together for speed to add to the curry all at the same time. Some add enough oil & salt to their base so they don't need to add more making the curries. The mix powder method of making curries is predominant on this forum, but they are only different methods of achieving roughly the same thing. The base gravy can be thick or thin also, with thin requiring reduction in the pan. I would guess there's more methods that are not on this forum, but everything you need is on here to get you started
None of the places I buy from in Glasgow use mix powders when making the curries, except for garam masala.
The spicing is done when making the base gravy(which does use powdered spice) & in the pre cooking of meats & vegetables. That way the spice is cooked for longer & produces a better flavour in my opinion
A Glasgow takeaway / restaurant bhuna as i know it & if made with a bit of care, will typically differ from a basic curry by adding more tomato puree, garlic ginger paste & less onion gravy (base)used, giving a darker, slightly drier curry & completely different flavour. A madras will have more tomato puree still, lots of blended fresh chillies in a paste & lemon juice. A south Indian garlic chicken dish will have a big spoonful of pre made 'south Indian sauce' added
Being Scottish you could try the Ashoka stuff below, which has different method again. Maybe to give you something to aim at?
]https://curry-recipes.co.uk/curry/index.php/topic,5355.0.html]Regards
ELW