Cook garlic, chile, and oil in a large high-sided skillet over medium-low heat, stirring, just until fragrant, about 2 minutes. Add tomatoes, one at a time, puzzling together into a snug single layer with little overlap (like filling a fruit tart). Leave out any that don’t fit. Scatter olives over top of and in between tomatoes. Increase heat to medium-low so is oil simmering very lightly, cover, and cook 2 minutes. Uncover and scatter oregano over tomatoes. Cover again and cook tomatoes until warmed through and very fragrant but not falling apart, 3–5 minutes more.