First you need to learn more about them

Those dwarves are strange. They are definitely not from Blue Mountains, ancient home of goblins that they lost to the Dwarwen Empire. First of all those two have no beards.,. by choice. They are cleanly shaven. No self-respecting dwarven woman would do that. They wear no armor and their shields are made from wood. They are armed not with swords but with spears (now harmlessly laying on the floor)

"So" you start looking straight in the eyes of one of the captives "Who are you and why are you trespassing through lands of my tribe?" Answer is exactly the one you would expect from stubborn dwarves - silence

"Listen" You start walking around your captives as they stand on their knees with their hands bound. It is strange how curvy those two are, not a typical body type for a dwarf. Looking at them from behind you note that their lower curves are as pleasant to the eye as their upper curves "I am busy. I have no time to play your games. No answers mean tortures. I'll start with **** one of you in front of another. Saying what I want to hear may delay this or even prevent such fate altogether. So, I ask nicely for one more time. Who are you?"

"We are travelers, We arrived from a distant realm and want nothing more but visit our relatives in Blue Mountains" One of them starts to talk almost immediately. She has a melodic low voice that fits her beauty perfectly "We didn't know that this lands are claimed and can pay all necessary tolls for the passage"

"Relatives in Blue Mountains? So, you have relatives among those slavers? That alone means that both of you deserve ****" You say harshly "Why did you shave your beards? Did you try to not look like dwarves to fool us?"
"Why?" The second one asks in a much higher voice. Looks like you got a great way to distinguish them "Are you blind or stupid? We are women. " The second one has much more boldness in her words. "Are you goblin? I read about vile creatures like you in books and you are even uglier and stupider than I imagined!"

"Sister!" The other one seems to understand that insulting someone who has your life in his hands is a bad idea.. Question is how will you react to an insult from the lips of a female dwarf