Step 1 Coat a 4cm-deep 16x24cm heatproof dish with cooking-oil spray. Pour milk and stock (or water) into a medium saucepan set over medium heat and bring to the boil. Add polenta, whisking, in a steady stream. Cook, stirring, for 5 minutes, or until mixture is thick. Pour into prepared dish and smooth surface. Refrigerate for 15 minutes, or until firm.
Step 2 Meanwhile, spray the base of a medium saucepan with cooking oil; set over medium heat. Add onion and garlic; cook, stirring, for 5 minutes, or until soft. Add sugar, tomato, capsicum and half of the vinegar; bring to the boil. Reduce heat to low and simmer for 10 minutes, or until mixture thickens. Set aside to cool.
Step 3 Preheat a grill pan set over medium-high heat. Turn out polenta, slice into 4 same-size rectangles, then halve on the diagonal to form triangles. Spray polenta triangles with cooking oil; grill for 2 minutes per side, or until golden and heated through.
Step 4 Meanwhile, bring a large saucepan of water to the boil. Reduce heat to medium. Add remaining vinegar and stir the water with a wooden spoon to make a whirlpool. Crack 1 egg, carefully, into the centre of the whirlpool; poach for 3–4 minutes (for a soft egg), or until cooked to your liking. Scoop up poached egg with a slotted spoon and transfer to a plate. Repeat with remaining eggs.
Step 5 Microwave beans according to packet instructions, or until just tender. Drain.
Step 6 Top grilled polenta triangles with poached egg. Serve with tomato relish and beans.