Yes, the sentence is in the present tense.
The oranges this season taste sour.
taste
The present tense of tasted is taste(s).
taste
It is "taste/tastes".
Orange (the fruit and the color) is a noun (or adjective) and does not have tenses like past, present, and future. Tense applies to the verb. The oranges will roll down the hill The oranges are rolling down the hill The oranges rolled down the hill Same oranges
have/has tasted
The word tastes is a verb. It is the present tense of taste.
The verb is is the present tense.
The future tense is will taste.
The past tense of did is did. The present tense of did is do. The future tense of did is will do.
It was, (past tense) it is, (present tense) it will be( future tense)