Braised Beef with Red Onion Gremolata

Bring to a boil, reduce heat, and simmer until reduced by half, 10–12 minutes.

Add garlic and broth and return to a simmer; add roast and thyme.

Cover and braise in oven, turning roast occasionally, until roast is tender, 2 1/2–3 hours.

Transfer roast to a large baking dish and strain braising liquid over.

Cover and chill onions.

Cover roast at least 12 hours.

DO AHEAD: Roast can be braised 2 days ahead.

Keep chilled.

Combine onion and vinegar in a medium bowl.

Let sit 30 minutes; drain.

Add chile, basil, chives, parsley, and lemon zest and toss; season with salt and pepper.

Scrape fat from beef; discard.

Transfer beef to a cutting board.

Bring solidified braising liquid to a boil in a large saucepan.

Reduce heat and simmer, stirring occasionally, until reduced to 2 cups, 25–30 minutes.

Add vinegar and braised onions; season sauce with salt and pepper.

Place flour in a shallow bowl.

Remove twine from roast and slice into eight 1–1 1/2" pieces; season with salt and pepper.

Heat oil in a large nonstick skillet over medium heat.

Working in batches, dredge meat in flour and cook until browned and crisp, about 4 minutes per side.

Arrange on a platter and drizzle with sauce; top with gremolata.