By the Word of the Lord the heavens were made (Psalm 33:6) God made everything, man from dust, etc. So why would changing water to wine at Cana be difficult?

“…for our nature, weakened by sin, it is an unattainable miracle. Yet, isn’t the working of miracles the usual occupation of the Creator? When the servants filled the six large vessels with water, the Lord Christ said to them: Draw out now, and bear unto the governor of the feast (John 2:8). He did not even say, ‘Let the water become wine,’ he merely thought it. For God’s thoughts have the same power as His words.

“Why is it said that this was the ‘beginning of miracles,’ when it appears that, long before this miracle, the Lord worked other miracles? Because, brethren, the changing of water into wine is the fundamental miracle of Christ, and is the essence of all His miracles. Human nature was diluted with its own tears, and it was necessary to change it into wine. The divine spark in man was extinguished, and it was necessary to rekindle it. Infirmity is like water, health is like wine; the impurities of the evil spirits are like water, purity is like wine; death is like water, life is like wine; ignorance is like water, truth is like wine. Hence, whenever the Lord made the sick whole, the impure pure, the dead alive, and prodigals enlightened, He essentially turned water into wine.”

-St. Nikolai Velimirović 

Read the entire homily here (scroll down to the bottom): Prologue of Ohrid