Chop the leeks, carrots, tomatoes, and potato; mince the garlic.
Heat the oil in a large, heavy-bottomed stockpot over medium-low heat.
Once oil is hot, add the leeks, garlic, salt, and pepper and cook approximately 7-8 minutes until they begin to soften.
Add the carrots, potato, and green beans and continue to cook for 4-5 minutes more, stirring occasionally.
Add the broth. Increase the heat to high; once boiling, reduce the heat to a simmer.
Add the tomatoes and corn kernels.
Reduce the heat to low; cover, and cook approximately 30 minutes more until the vegetables are tender.
Remove from heat, then add in parsley and juice from the lemon; add more salt and pepper to taste.
Toast each slice of bread and slice the avocado.
Top each piece of toast with some avocado slices, a dash of hot sauce (if desired) and a sprinkling of salt and pepper.
Serve soup with toast and banana slices on the side.