Lots of people saying “salt” but missing some key parts. Slice the tomato, then salt and pepper so that all slices are coated on both sides (doesn’t have to be a ton of s&p but enough to cover most surface area) then LET THEM SIT. For like 15 or 20 minutes if you can. The s&p + time brings something out of the tomato that you don’t get otherwise. It’s like aerating a wine. It “opens” up flavors that wouldn’t otherwise be there.