Slow-walking impeachment may look weak. But restraint is Democrats’ greatest strength.

There was only one side of the dais at Tuesday’s House Judiciary Committee hearing that mentioned impeachment — and it wasn’t the Democratic side.

There was only one side that hollered and sputtered, one side that lobbed insults at the other and impugned colleagues’ motives — and it wasn’t the majority.

Indeed, Tuesday’s hearing was a study in the asymmetric combat that defines our politics in the Trump era. Some on the left see this asymmetry as a sign of Democratic weakness. I see it as the nation’s best hope for recovery.

At Tuesday’s session, the committee’s chairman, Rep. Jerrold Nadler (D-N.Y.), spoke in a calm, steady voice about the absence of former White House counsel Donald McGahn, a no-show after President Trump ordered him not to comply with a subpoena. “Mr. McGahn has a legal obligation to be here for this scheduled appearance. If he does not immediately correct his mistake, this committee will have no choice but to enforce the subpoena against him,” Nadler intoned.

Nadler mentioned neither impeachment nor contempt, and he managed to keep the Democratic side — including the gadfly who brought fried chicken to a previous hearing as a prop — quiet.

Then came Nadler’s Republican counterpart, Rep. Douglas Collins of Georgia, who practically yelled out his statement and fired off taunts so quickly that those of us in the room struggled to understand him, and the transcript designated several sections as unintelligible. The words that did come through were mostly caustic and personal. Nadler “rushed to maximize headlines,” was “politically expedient,” issued an “illegal subpoena,” “orchestrated” a “spectacle” and a “drama,” and is “more interested in the fight than fact-finding.” Collins further accused Nadler and the Democrats of “harangues,” “innuendo” and warned of“running roughshod over the Constitution.”

“The theater is open,” Collins said of the sedate proceedings. Because Democrats can’t find anything to “hang their I-word, impeachment, on. . . . We’re here again, with the circus in full force.”

Though accusing Democrats of theatrics by having the empty-seat hearing, Republicans attempted to continue bickering by voting against adjournment. “This is disgraceful!” cried out Rep. Steve Chabot (R-Ohio).

Watching this disparity in demeanor, I tried to imagine how things might look if Hillary Clinton had won the presidency, and, two years later:

• Five of her campaign advisers had been convicted of crimes — one of them implicating her — and a sixth indicted.

• A prosecutor documented numerous instances in which Clinton had interfered with investigators.

• Clinton refused to let aides cooperate with subpoenas and dismissed an unfavorable court ruling as “crazy” and partisan.

• She directed the Justice Department to investigate the front-runner for the Republicans’ 2020 nomination.

• She directed the White House counsel to lie about her deceit, then ordered him not to testify.

Can anybody imagine, in those circumstances, a Republican speaker of the House and the Republican presidential front-runner (the one Clinton ordered investigated) steadfastly resisting calls for impeachment?

There is long-standing tension among Democratic lawmakers and 2020 presidential candidates about whether to answer Trump’s aggression and insults in kind (Republican lawmakers long ago internalized his style) or whether to be the grown-ups in the room. On the campaign trail, Sens. Elizabeth Warren (Mass.) and Kamala Harris(Calif.) have called for impeachment, and a growing number of Democrats in Congress, from fiery Rep. Alexandria Ocasio-Cortez (N.Y.) to Rep. David Cicilline (R.I.), a member of Speaker Nancy Pelosi’s (Calif.) leadership team, have joined the cause. Liberal activists rage against Pelosi “meeting fire with fecklessness,” as New York magazine’s Eric Levitz put it.

But the mass of voters side with restraint, and even anti-establishment Sen. Bernie Sanders (I-Vt.) has said impeachment “works to Trump’s advantage.” Certainly, Trump has earned impeachment; Republican Rep. Justin Amash (Mich.) has said as much. But with no chance of removing Trump, Democrats can instead show the country that our problem isn’t polarization; it’s that one side has gone bonkers, and the other side is trying to restore adult supervision.

Americans, even reluctant Trump supporters, hunger to end the madness. This is likely why former vice president Joe Biden holds a commanding lead, even though he’s out of sync with the party base ideologically and demographically. And generally, the 2020 Democrats seem to grasp the country’s need for normal. I had feared that, after Trump, Democrats would conclude there’s no penalty for lying. Instead, “anecdotally, I think they are trying to harder to be more factually accurate,” The Post’s Fact Checker, Glenn Kessler, tells me.

This is an encouraging sign, as is party leadership’s efforts to resist an impeachment stampede. Impeachment may be inevitable if Trump continues to stiff-arm all inquiries. But Democrats are right not to emulate Trump’s insults, falsehoods and extreme partisanship as they go about their legitimate inquiries.

Maybe such restraint will be proved wrong in 2020, and voters will reward the insult hurlers. But if Americans don’t desire a return to stability, honesty and decency, our democracy is already lost.