8 red bell peppers
2 garlic cloves, very thinly sliced
1/4 cup olive oil
2 tablespoons (or more) sherry vinegar or red wine vinegar
2 tablespoons chopped marjoram, divided
Heat broiler. Place bell peppers on a rimmed baking sheet. Broil, turning occasionally, until skins are blackened and blistered all over, 14–17 minutes. Transfer peppers to a large bowl, cover with plastic wrap, and sweat 15 minutes.
Remove skins and seeds from peppers; discard. Tear peppers into about 2"-wide strips. Toss in a clean large bowl with garlic, oil, vinegar, and 1 Tbsp. marjoram; season with salt. Let sit at least 20 minutes and up to 4 hours.
Just before serving, taste peppers and season with more vinegar and/or salt if needed. Scatter remaining 1 Tbsp. marjoram over top.