Everton claimed their first win of the season, beating Brentford 3-1 to end a 13-match winless streak in London league matches and move out of the relegation zone.
Doucoure almost doubled the lead on 27 minutes, but his shot cannoned off the crossbar.
Both teams had further chances to score in an open match, but the next goal did not come until the 67th minute when Tarkowski glanced in Dwight McNeil’s corner on the six-yard line against his former team.
It was the defender’s ninth Premier League goal in total and sixth from a corner, the other three coming from free-kicks, all under Sean Dyche.
Everton climb to 15th with four points.
Brentford, who lost Kevin Schade to a serious-looking injury in the warm-up, seemed flat throughout, having only two shots on target. They drop to 12th on six points after slumping to a second consecutive defeat.