In English, the main clause of a conditional sentence does not require a conjunction. It is grammatically correct to say:
If it rains tomorrow, I will take my umbrella.
I will take my umbrella if it rains tomorrow
If it rains tomorrow, then I will take my umbrella.
The "else" clause does require some words such as "Otherwise", or "if not" to distinguish it.
If it rains tomorrow, I will take my umbrella. Otherwise, I'll just wear my jacket.
Your example is not very clear, and doesn't involve logic. Instead when you say:
If I tell you how this ice cream tastes, it is delicious.
I think you mean
If I were to tell you how this ice cream tastes, I would tell you that it is delicious.
That uses a subjunctive and a conditional expression but is rather odd. Why make it a condition? This is a very long and confusing way of saying
This ice cream is delicious.
Or perhaps, with a bit more style:
Let me tell you how this ice cream tastes. It's delicious!