The second question does not ask if they have had an experience. Rather, it asks a question about a particular experience that you know they had. Here's a question about an experience: "Have you enjoyed a smoothie?". If the answer is yes, you can ask "What flavor was it?"

In the US, it's probably more natural and common to say: “Have you ever had a mango smoothie?” or “Have you ever tried a mango smoothie?” The follow up, “Did you like it?” then is consistent with the first question. It's understood that ‘to have/had’ in this case means to drink. The inclusion of ‘ever’ signifies/specifies that you're asking if the person has ever tried a mango smoothie in their entire life versus recently. If you were at a particular restaurant (or were talking about a particular restaurant), and you used ‘the mango smoothie,’ it would signify that you're talking about the specific mango smoothie sold by that store.