Add onions and garlic to skillet. Cook dinner, stirring typically, till onions are translucent and starting to brown on the edges, 6–8 minutes. Scale back warmth to medium-low and stir in tomatoes. Cook dinner, stirring often, till combination is jammy, 5–7 minutes. Stir in potlikker and pink pepper flakes, season with salt and pepper, and produce to a simmer.