In a heavy saucepan or Dutch oven, sauté the onions in 1/3 cup olive oil along with a generous pinch of salt on medium-low heat, until the onions are lightly caramelized, 10-15 minutes. Add the garlic and continue to cook for another 5 minutes. As the onions darken, stir to keep from burning.
Either puree the tomatoes with a hand blender or roughly grate with a cheese grater.
Once the garlic is fragrant and soft, add the coriander, tomatoes, chili, and another pinch of salt.
Raise the heat to bring the mixture to a simmer, then lower the heat to maintain the simmer. Cook, uncovered, for 25-35 minutes or until the tomatoes break down completely.
In a medium pan over medium-low heat, warm the neutral oil. When the oil shimmers, add the green beans, another pinch of salt, and the black pepper. Cook for 7-10 minutes, or until the beans are soft. Then add the tomato sauce and the lemon juice and mix thoroughly.
To serve, transfer the beans to a serving plate. Drizzle with the olive oil and sprinkle with optional Maldon salt for garnish.