1-1/2 lb fresh sashimi grade tuna
Avocado cream -
1 ripe avocado
2 hours before serving - Begin by preparing the tuna.
Tuna - Slice the tuna along the grain 1/4" thick. Cut each slice lengthwise and chop each length to get 1/2" cubes. Continue till all the tuna is cut this way into 1/2" cubes. Remove to a glass bowl and set aside. Squeeze the juice from the limes & the lemon in a bowl. Add the lime-lemon juice to the chopped tuna. Stir and cover the bowl with a plastic wrap. Refrigerate immediately. Minimum refrigeration time is 1 hour.
Finely Chop red and yellow peppers, Add to large glass mixing bowl. Finely chop red onion. Chop cilantro. Quarter the cherry tomatoes and add to the bowl with the peppers, onion and cilantro.
Cut an avocado into hallves. Remove the seed and scoop out the flesh. Chop into 1/2" cubes and add to bowl with the remaining ingredients. Add the jalapeno pickling liquid, olive oil and salt. Stir till well combined. Cover the bowl with plastic wrap & refrigerate.
Avocado cream -
Chop the remaining avacado as described above and place in a bowl along with mascarpone, sour cream and lime juice. Keep stirring with a spoon till the avocado is mashed up & thoroughly blended. Cover the bowl with plastic wrap & refrigerate.
Char the peppers directly on gas flame or grill. Use tongs and keep turning over so the peppers are charred on all sides. If using an electric stove, use the broil setting in your oven. Broil till completely charred and blistered.
Place the charred peppers in a zip lock bag. Seal and set aside for 10 minutes to steam the peppers. This will allow the skin to come off quite easily. Remove as much charred skin as practical, but don't obsess over it. You can take a moist kitchen paper towel and wipe off the surface to get any excess charred skin off.
Halve the peppers & remove all ribs, membranes and excess seeds. Lay all the peppers on a flat platter ready for assembly.
Remove the tuna from the refrigerator and drain any excess liquid off by straining in a sieve. Add the tuna to the large mixing bowl with the remaining ceviche ingredients. Stir. Taste & adjust seasonings.
To each pepper half, spoon the tuna ceviche till full. Top with a spoonful of the avocado cream and a cilantro leaf for garnish.