The Sharks are rooted to the foot of the Premiership with just one win from 10 matches but Mitchell, the club's newly appointed director of rugby, was encouraged by the way they made star-studded Toulon fight all the way for the points in today's Pool Six game at the Salford City Stadium.
"It was a privilege to play against such a side," Mitchell said. "It's quite exceptional in world rugby to have a club side that has icons from South Africa, Australia and England in Bakkies Botha, Matt Giteau and Jonny Wilkinson. They are special days in one's rugby life so I couldn't think of a better side to test the character of the group."
A second defeat to French opposition ahead of next week's re-match on the Cote D'Azure leaves the Sharks with little hope of qualification for the knockout stages, but their priority is the Premiership and Mitchell believes today's performance was a major improvement on last week's home defeat by Northampton.
Toulon winger David Smith scored the only try of the match while captain Wilkinson kicked four goals from seven attempts to see off the challenge of Sale, for whom a recalled Danny Cipriani kicked two penalties.
Mitchell added: "After last week one thing we asked of the guys in order to move forward - we need to basically stay in the contest for a lot longer and we managed to do that.
"I thought we fought very well and also showed more maturity than we did last week. We didn't get frustrated when we lost possession and we generated some exceptional work without the ball.
"I think an example of how much we've grown in a week was the way we defended our goal-line with about 12 minutes to go. It gives you a sign of where we've got to head towards in order to advance in the Premiership.
"The Premiership is not about being the most exciting football team - it's about being a collective team that's prepared to work together and hang in there. It was a very good collective performance.
"I think tonight we showed it's a good starting point. What we've got to do now is build on that each week."