Bring a pot of well-salted water to boil. Boil beans for 3.5 minutes (yes, I honestly believe that this level of timed precision will be rewarded). Plunge them into an ice bath and drain the beans
In your empty pot melt two teaspoons of butter over medium heat. Add the shallot and saute them until they’re just translucent, not browned–about one to two minutes.
Add the drained and cooled beans back into the pot and reheat them in the butter and shallots. Season with salt and pepper. Spread beans and shallot onto a plate, throw the diced tomato over them and squeeze a few drops of lemon juice over the dish.