In a large soup pot, fry the onions in the oil until light brown. Stir in the spices & toss in the peas & tomatoes. Stir again & cook for 5 minutes over moderate heat. Add stock, bring to a boil, cover & simmer until the peas are tender (at least an hour). Before serving, stir in the garam masala & fish out the cinnamon stick & cloves. Garnish with shallots.